The Science of Why Exercise Makes You Happy
Barbells, treadmills, and bliss.
On Fridays, I eat Qdoba.
The gym is quiet on Friday evenings. The power racks are empty, bars and plates neatly slotted in their places. The artificial turf is open, the yoga mats that crowd the floor on Mondays nowhere to be seen.
There are people, a few dudes benching or curling or pressing or shrugging, by the dumbbells. Maybe there’s a lone lifter cycling through the machines.
There are more people downstairs, in the cardio room. But the sound is not the endless blended “thunk” of 50 ellipticals. If you closed your eyes, you could count the number of machines by the noise.
It’s Friday night. Of course most people don’t want to work out. But Friday nights are my favorite.
On Fridays, there’s no waiting for equipment. There’s no asking to work in. There’s no maneuvering around people during farmer’s walks, or standing in line at the water fountain.
When I finish my workout, I set aside extra time to stretch and foam roll. I sit back and relax in the empty sauna. I stand under the showerhead and let the water wash away my sweat.
And as I stand in Qdoba, ordering a steak burrito with queso and extra guac, skin still warm to the touch, I feel an incredible lightness that can only mean the week is over.
That’s how exercise makes me feel, but you don’t have to take my word for it.
The effects of exercise on happiness and mood are well established by everyone from lifestyle bloggers to MD/PhD psychiatrists, and (spoiler alert) they’re good.
If you doubt the power of exercise, or even just want to know why it makes you feel the way it does, read on.
How Exercise Makes You Feel
Research has consistently shown that exercise improves your mood [1, 2].
Some have even argued that exercise is as effective as antidepressants or therapy in treating depression , and exercise can probably interact with other things to have even larger effects on your happiness .
In covering one study of adults with moderate depression, habits blogger James Clear pointed out why exercise makes you happy:
“Exercise does something that medication doesn’t. It proves a new identity to yourself. Each time you finish a workout, you reap the benefits of an increased sense of self–confidence. The cumulative impact of these “small wins” is enormous.”
There are psychological and physiological reasons that exercise is awesome, and we’ll dig into the details of each in just a moment.
But first, imagine asking someone who exercises regularly what impact exercise has had on their life.
Actually, you don’t have to imagine it; transformation stories are everywhere on the internet. Just Google “exercise saved my life.”
There are over 15 million results.
There’s a reason that the popular site Develop Good Habits lists “daily exercise” as the number one habit of happy people, and that Amit Amin of Happier Human says that “regular exercise increases happiness just as much as doubling one’s income would.”
There’s no shortage of experts or celebrities telling their story either. Michelle Segar, PhD, MPH, professor at the University of Michigan and the author of No Sweat, said in an interview that:
“I like to think of physical activity as a way to revitalize and renew ourselves, as fuel to better enjoy and succeed at what matters most.”
Henry Rollins, former vocalist for Black Flag, wrote an internet-famous essay titled “Iron and the Soul” in which he says that:
“The Iron is the best antidepressant I have ever found. There is no better way to fight weakness than with strength. Once the mind and body have been awakened to their true potential, it’s impossible to turn back.”
And of course, I’ve written about my own story about fitness, about what it feels like to be fit. The short version is this: exercise makes you happier, more energetic, and more confident.
I was curious; so many people talk about the wonders of exercise, but it seemed like no one could answer the question of why. I scoured the internet and came up with…not much.
There are lots of blog posts and articles out there, but they all seemed to stop short, saying something to the effect of “endorphins!” plus some hand waving.
Endorphins can explain a post-workout high, but what about increased confidence? What about long term change? The answer wasn’t clear.
There’s nothing more dangerous than a curious nerd with a question, and I dove into the psychology and neuroscience research to get to some answers.
In part one of this article, I’ll highlight the psychological reasons behind why exercise makes you happy. You’ll find that they apply to happiness in general, but also suggest ways to get yourself to work out more consistently.
In part two, I dive into some neuroscience to show that, although endorphins are definitely a possible cause of happiness after exercise, they are far from the only cause. If you feel terrible after exercise, you’re probably working out harder than these processes can account for.
(In fact, there probably isn’t a single physiological reason that exercise affects mood. Exercise has an effect on an incredible number of aspects of your neurology. Still, I lay out the current state of the research)
But instead of slapping down a conclusion at the end, I’m going to give you some of the big insights up front. Why should you care why exercise makes you happy?
If you ever have trouble working out consistently, and we all miss days occasionally, focusing on the psychology of what makes exercise awesome can help you refocus — and focus on things you love instead of things you hate.
The psychology of why exercise makes you happy suggests that you should:
- Focus on making tangible progress (as in, every workout) towards well-defined goals
- Choose your goals, and specific exercises, based on what you personally like and value
- Use exercise a reset for when you’re worrying, to get things under control
- Make friends! Exercising with friends makes you happier and more consistent
- Do exercise that feels good. If you feel terrible, you’re working out harder than dozens of physiological processes can make up for. Take it easy and ramp up over time.
Part 1: The Psychology of Why Exercise Makes You Happy
Exercise can affect long-term happiness because it contributes to other things that increase long-term happiness.
In that sense, there’s nothing unique about exercise. It just happens to check a lot of the boxes for things that we know make people happier.
I would argue, however, that exercise is especially good at checking a lot of these boxes, and that some boxes are much, much harder to check off using other methods.
Can you be happy without exercise? Of course! But there’s no other single activity that fulfills so many fundamental psychological needs.
But before we talk about those, let’s cover some of the things that don’t make us happy — even though we think they do. The time and energy we waste on these fruitless pursuits make the real causes of happiness (the ones exercise can help) even more important.
Things that Don’t Make You Happier: The Hedonic Treadmill
Psychology research has revealed quite a few factors that make people happier or less happy.
It has also revealed an unpleasant truth: we are terrible at knowing what will make us happy.
This finding is at the core of Harvard professor Daniel Gilbert’s book Stumbling on Happiness.
As Gilbert writes:
“We treat our future selves as though they were our children, spending most of the hours of most of our days constructing tomorrows that we hope will make them happy… But our temporal progeny are often thankless.
We toil and sweat to give them just what we think they will like, and they quit their jobs, grow their hair, move to or from San Francisco, and wonder how we could ever have been stupid enough to think they’d like that.
We fail to achieve the accolades and rewards that we consider crucial to their well-being, and they end up thanking God that things didn’t work out according to our shortsighted, misguided plan .”
The point is, of course, that we don’t know what will make us happy. That’s why “our temporal progeny” is thankless — the things we do in the present often don’t affect our long-term happiness.
This goes for just about everyone. I’ve read plenty of this research, and I guarantee I make this mistake all the time (I’m even shopping for a new laptop as we speak). Gilbert literally wrote the book on the subject, and I’d be willing to bet he’d be the first to admit his misestimation.
And one major cause of our misestimation is the hedonic treadmill.
The hedonic treadmill is the idea that we begin adapting to new experiences and possessions as soon as we have them .
If you suddenly moved into a mansion, you would become happier — for a little while. But before long you become used to the backyard pool and 16 bathrooms. It becomes just another part of everyday life.
The same is true of money . People often strive to make more money, to work harder and get that next promotion. But the research shows that money only increases happiness when it lifts you out of poverty and fulfills your basic needs.
Take lottery winners as an extreme example. I can only imagine the spike in happiness that occurs immediately after winning the lottery.
While we’re at it, imagine a horrible accident that leaves you paralyzed and unable to walk. Hard to imagine a bigger spike in negative emotion.
And yet, one year down the line, lottery winners are not significantly happier than before they won the lottery and paraplegics are not significantly less happy .
Many people think that attractive people are happier than unattractive people. But this turns out not to be the case either .
We adapt, or habituate, to our environments. Getting more stuff doesn’t make us happier, and losing lots of stuff doesn’t make us less happy.
And yet, amazingly, even people aware of this research often don’t believe it. I have personally witnessed people say things like “Money can’t buy happiness, but I’d rather cry in a lamborghini.”
Personally, I’d rather not cry at all.
As Gilbert notes, our inability to figure out what makes us happy before it happens causes problems:
“The fact that we often judge the pleasure of an experience by its ending can cause us to make some curious choices.”
We pick up extra shifts to buy a new computer instead of spending time with our family. Or skip the gym because we just aren’t in the mood and need to relax.
Again, I’m personally guilty of this too. There are absolutely days where I’m tempted to skip the gym and go eat dinner. Or, more often, skip the post-gym sauna and get home quickly.
But after I spent some time recording my expected happiness and comparing it to my actual happiness, a technique borrowed from cognitive behavioral therapy , I realized that I was actually happier when I followed through.
Bottom line? People are terrible at predicting happiness.
Materialism won’t make us happier, but there are (fortunately) other things that do. These are the things exercise contributes to.
Things That Do Make You Happier
We may be bad at predicting what makes us happy, but research has helped us identify the things that really matter.
Gretchen Rubin, author of The Happiness Project, has talked about how exercise makes her feel. Notice the lack of material explanations:
“When I’m feeling blue, exercise helps a lot. Perhaps that’s because when I’m exercising, I’m distracted and not ruminating on anything that might be upsetting me.
Maybe it’s because exercise boosts energy, and feeling energetic helps people feel cheerier.
Maybe it’s because I know that exercising will help keep me healthy, so I feel good about doing something that’s good for me.
Maybe it’s because just the sheer ticking-an-item-off-the-to-do-list is satisfying.
Or maybe it’s just that I expect that exercise will make me feel better, and so it does.”
All of these explanations are relevant, and some will be discussed in the next section. For now, the key psychological factors that increase long-term happiness, and that exercise can affect, are:
- Consistent progress towards goals
- Personal control and self-efficacy
- Removal of negative influences
- Strong relationships
Consistent Progress Towards Goals
When you work towards a goal, there are two kinds of satisfaction: the satisfaction of achieving the goal, and the satisfaction of every single step you take along the way.
The saying “it’s the journey, not the destination” is almost a cliche — but as YouTube personality Shay Carl says, “The secrets of life are hidden behind the word cliche.”
The problem with the destination is that there is usually only one destination. When you achieve your goal, you get a quick hit of pleasure and achievement…but you then adapt to your new level of achievement the same way you adapt to everything else.
When you focus on the journey, on the other hand, every single step is a reward. You adapt to each step, sure, but there’s always a next step to take.
This is borne out in the psychology research. In comparing pre-goal positive affect (good feelings during the journey) and post-goal positive affect (feelings caused by the destination), research found the pre-goal effects to be more enduring and to have a larger effect overall .
And as anyone that’s consistently worked out will tell you, progress in fitness feels amazing.
When you start out, adding weight every session makes you feel strong and capable. You can see your progress easily.
When you are more advanced, every PR is a huge accomplishment.
You can also experiment with more challenging exercises. Scott Young writes about mastery and personal development, and once wrote about his experience learning handstand push-ups:
“Part of the reason I’ve enjoyed bodyweight fitness is that it is very satisfying to complete a particular exercise for the first time.”
Nerd Fitness’ Steve Kamb says something similar:
“Ensure with each workout you are doing something better, stronger, or faster than the previous workout. Just as importantly, make sure you recognize that you are improving.”
Exercise makes you happy because you are constantly working towards a goal, constantly bettering yourself.
Every workout carries with it a sense of achievement.
Importantly, the kinds of goals exercise creates magnify the effects of happiness from progress. More on that in the next section.
Personal Control and Self Efficacy
People have a psychological need for control .
If you think about the most stressed you have ever been, it probably coincides with a time where there was something worrying that you couldn’t control.
It is unsurprising, then, that people who perceive things as out of their control — which is called having an “external locus of control” — are more likely to suffer from depression and anxiety .
Self-efficacy is related, and is your belief in your own abilities regarding a specific task or topic. Believing in your own abilities makes you more likely to achieve goals .
In situations where you feel powerless, it is sometimes valuable to seek out some, any, form of control.
In my last week of college, I received terrible news over email — I needed to completely rewrite a semester-long research paper, from scratch, in the next 48 hours. Not doing so would prevent me from graduating.
This was a research-based paper. I had zero sources in-hand and little background knowledge on the topic. Before getting this email, I was one (easy) final away from being finished with undergrad.
I needed to write 15 pages in 48 hours, and the paper was worth something like 70% of my final grade for that class. So what was the first thing I did?
I needed to do something normal. It felt like things were spiraling out of control, so I took a step back to do something I knew I could control.
Of course, terribly ironically, my hands were shaking so much that I took a huge chunk of skin out of my head and had blood pouring down my neck.
But even dealing with that gave me something to do, something to control. It helped me calm down, I busted out the paper in 12 hours (for a B+. Could have been worse), and I graduated no problem.
What does that have to do with exercise? Exercise is something you can control.
When you go to the gym, you decide what you do. You decide when you do it. There is no one to boss you around and no obligations to fulfill. Just you and the workout.
Tying this back to goals, research shows that you’re more likely to get long-term satisfaction from goals if they are goals that you set independently, goals that you have complete control of and ownership over [15, 16].
Remember the Henry Rollins essay I mentioned earlier? Part of what makes “the Iron” so important to Rollins is the control:
“I saw a body, not just the shell that housed my stomach and my heart. My biceps bulged. My chest had definition. I felt strong. It was the first time I can remember having a sense of myself. I had done something and no one could ever take it away.”
In most spheres of your life, you have to give up some control. Exercise is a rare time that isn’t true, and that makes it incredibly therapeutic.
Control is the second reason exercise makes you happy.
Removal of Negative Influences
Remember what Gretchen Rubin said earlier about exercise?
“When I’m feeling blue, exercise helps a lot. Perhaps that’s because when I’m exercising, I’m distracted and not ruminating on anything that might be upsetting me.”
This turns out to be remarkably accurate.
One of the prominent ideas about why exercise makes you happy is the distraction hypothesis.
The idea is simple: when you are exercising, you aren’t worrying about your problems . You’re focused on the task at hand, and there isn’t room to think about other things.
This idea has some credibility based on what psychologists know about worrying. Ruminating, or thinking endlessly about your problems, is associated with higher rates of depression and anxiety .
If exercise can stop you from ruminating, it makes sense that it would improve your overall happiness.
The research on meditation and mindfulness has similar findings; a major reason mindfulness is helpful is that it takes your attention away from things you can’t control .
Frankly, it’s hard to stay upset during a workout.
Another possible explanation is that exercise can actually entirely remove some negative influences.
I mentioned earlier that physically attractive people are not happier than physically unattractive people, and that’s true. But people that become physically attractive do experience a marked increase in happiness .
The reasons for this are not entirely clear, but one possible explanation is shame. If you are ashamed of your appearance and your appearance improves, you’ve removed a major source of stress.
It’s no secret that exercise can improve physical attractiveness; it’s one of the biggest reasons people work out.
Improving your appearance alone probably won’t improve your happiness hugely. But, combined with these other factors, it can contribute to making you happier overall.
There may be nothing more important to happiness than personal relationships.
Close personal relationships have an enormous effect on our psychological well-being, to the point where they can even be considered a psychological need .
As importantly, personal relationships are something you never adapt to. Unlike material possessions, a relationship doesn’t get less satisfying the longer it lasts .
Although I’m noting that personal relationships are the biggest driver of happiness on this list, I’ve marked it last on the list because exercise doesn’t necessarily lead to close relationships.
It’s true that exercise can be a great way to meet people, but if you just go to the gym, work out, and get out, you probably won’t actually meet anyone or get close to anyone.
And that’s fine.
These days, I work out alone 99% of the time. I probably won’t even say a word the entire time I’m at the gym, other than “are you using this” or “do you know if this bench is taken.”
And personally? I like it that way. It’s fine to work out like that.
But there are also ways you can build those personal relationships if you want to.
When I first started working out, I had a lifting buddy. I’ve had several lifting buddies over the years, and some of them are still close friends.
I’ve made some of my best friends through my college ultimate frisbee team.
I’ve had short-term roommates that I was able to bond with because we both worked out, and occasionally I’ll get on head-nod terms with a dude I see at the gym all the time.
Some people have a lot of success with group fitness classes at the gym, yoga sessions, or running groups. Social connections can be a powerful motivator.
So if your goal for fitness is well-being, it might make sense to work out with someone else.
Part One Summary
People suck at figuring out what makes them happy, and there are a few things we spend time pursuing that don’t actually make a difference.
- Material possessions
Our psychology is such that we habituate to these kinds of things. That is, we get used to them, and an initial surge of happiness fades over time. This is called the hedonic treadmill.
On the other hand, there are some things that lead to lasting happiness. Exercise can make you happy because it affects each of these things.
- Consistent progress towards goals: It’s easy to set up and eventually achieve skill and strength goals for exercise.
- Personal control and self-efficacy: Exercise is something that you have complete control over.
- Removal of negative influences: Exercise can prevent you from worrying about stuff you can’t control.
- Strong relationships: If you want, exercise can lead to powerful personal connections.
These are psychological reasons that exercise can lead to short and long-term happiness. In part two, let’s take a look at physiology.
Part 2: The Physiology of Why Exercise Makes You Happy
The physical side of exercise and happiness is enormously complicated, and an enormous subject of debate.
Although there are dozens of potential causes, most of the research  circles back to two main ones:
- Neurotransmitters (especially serotonin)
- Endogenous opioids (aka endorphins)
This section will focus on these two, then mention some of the other interesting contributors.
If you don’t really care about what’s going on in your brain, feel free to gloss over this. If you have a PhD in neuroscience, this is probably going to bore the shit out of you.
Anyone else, keep reading!
Neurotransmitters are how your brain cells talk to each other.
Essentially, one brain cell releases a chemical in the direction of another cell. That other cell receives that chemical through special doors that only specific chemicals can fit through. The first cell then reabsorbs any leftover neurotransmitter.
The steps are:
- Release neurotransmitter
- Receiving cell snags some neurotransmitter
- First cell takes back the leftover neurotransmitter
On its face, the process isn’t that complicated.
It gets a little more complicated once you consider that different neurotransmitters do different things.
It gets a lot more complicated once you consider that the same neurotransmitter has different effects in different parts of the brain.
And it gets almost impenetrably complicated once you consider that the effects of neurotransmitters can overlap and influence each other.
One of the major roles of neurotransmitters is in changing your mood. The most commonly prescribed class of antidepressant drugs, SSRIs, have an effect on the neurotransmitter serotonin.
Interestingly, exercise affects serotonin levels similarly to SSRI drugs .
From there it gets tricky. SSRI stands for “selective serotonin reuptake inhibitor.” These drugs interrupt step three of the neurotransmitter process (hence, “reuptake inhibitor”), they do it to serotonin, and they do it to only some parts of the brain.
That lets the receiving cells pick up more serotonin than usual, affecting mood.
But with both exercise and drug research no one actually knows why that improves mood. Sure, there’s more serotonin just chillin’ between cells (and the effects are also a little more nuanced than that). But what happens next?
One of the more popular theories is that the change in neurotransmitter levels helps you make new brain cells . The idea is that depressed people have an unusual amount of cells dying…for some reason… and that this specifically happens in the hippocampus, the brain area related to long-term memory and navigating physical space.
The increase in serotonin might help those people’s cells not die, and help them make new brain cells.
Of course, this explanation probably wouldn’t explain the immediate “high” you get from exercise; your new cells don’t suddenly wink into existence with every rep. Man-made versions of this effect (i.e. drugs) take a few weeks to really kick in.
And if that isn’t mysterious enough, there are other neurotransmitters affected by exercise.
Exercise has been shown to increase levels of brain-derived neurotrophic factor (BDNF), which helps you make new brain cells .
But of course, it couldn’t be that simple. Even if BDNF levels change, if they change without a change in serotonin it’s still possible for there to be no change .
So when it comes to the role of neurotransmitters in exercise and happiness, it seems like part of the effect might be because of new brain cells.
The point of all this? This is complicated. We have a sense of some things that are relevant, but it’s going to take a lot more research to figure out what’s actually happening.
Endorphins are the explanation that shows up on every fitness blog on the internet.
And it’s true: endorphins are one of the leading proposed explanations for why exercise makes you happy. They are, after all, literally opioids.
But again, science is complicated. It’s too simple to say that endorphins are “the” reason exercise makes you happy.
What we can say is that they play a role, specifically with regards to exercise related “highs.”
In one study, researchers tested runners after a workout to see if there were differences in how opioids affect different brain regions. There were, and those changes were related to post-run euphoria .
In an even more convincing study, researchers gave participants a drug that blocks opioid receptors (preventing opioids from affecting the relevant brain areas). They found that people that took the drug didn’t have an exercise-related mood change compared to a placebo group .
And of course, although I’ve separated out neurotransmitters and endorphins, the two almost certainly interact. One common explanation for the role of endorphins is that they increase level of dopamine (another neurotransmitter) in the brain .
But can quick hits like this explain the long-term effects of exercise and happiness on their own? Maybe, maybe not. The science is still unclear.
Other researchers suggest that endorphins may impact mood by functioning as painkillers, changing pH levels after exercise, or regulating insulin levels .
Yet again, this research is complicated. If the answer were just serotonin or just BDNF or just endorphins, science would have already cured everyone and no one would be depressed. Everyone would be constantly elated by our non-addictive euphoria drugs.
And there are even other factors that are less well understood.
Quick Hits: Some Other Possible Causes of Mood Change
As I’ve been stating repeatedly, the human body is incredibly complicated, and that complexity makes it hard to root out a single cause of mood change.
In fact, there probably isn’t one.
There are several other possible causes in addition to the two most popular explanations above. In one review article, the authors list the following possibilities:
“Neurotransmitter processes, immuno-inflammatory pathways, hypothalamic-pituitary-adrenal (HPA) axis disturbances, oxidative stress and antioxidant defence systems, neuroprogression, and mitochondrial disturbances .”
The authors of the article conclude that exercise can reduce long-term inflammation, which is associated with depression.
They conclude that exercise can be considered an antioxidant, because doing it creates more antioxidant enzymes, and oxidizing free radicals may help depression.
They conclude that exercise has an effect on stress hormones, which are associated with depression.
Even if endorphins and neurotransmitters explain the bulk of the effect of exercise on mood, they probably don’t explain all of it.
The reason that this question is so difficult to answer, and the reason that it’s so hard to create effective antidepressant drugs, is that there are dozens of little changes that can affect mood.
And they all work together to change your mood post-exercise.
Part Two Summary
People are complicated.
Exercise is a complicated physiological event, and there are a lot of potential contributors to an increase in mood.
Endorphins and neurotransmitters are the two most frequently studied effects, but even then research tends to focus on distance running over other forms of exercise.
Exercise probably also decreases long-term inflammation and reduces free radicals, and in some circumstances (an intense competition or super heavy PR) it would even make sense for adrenaline to play a role.
In summing up, science has identified some processes that are probably related to mood, but it’s still unclear how many processes there are and how they interact.
For you, as someone who exercises, remember that exercise should feel good. If you feel miserable after exercise you are working out so hard that you’re overriding dozens of physiological responses designed to make you feel good.
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Originally published at routineexcellence.com on April 6, 2017.