The fight or flight response is a good illustration of how your brain and body work together as a system. To maintain your performance under stress, you need to be able to regulate this system. As William James, the father of modern psychology, noted: “The great thing in all education is to make our nervous system our ally instead of our enemy.”
To do this, think of your nervous system in three parts: your physiology, your emotions, and your thoughts. This interconnected system works both ‘top-down’ and ‘bottom-up’, so:
 • Your thinking affects how you feel, and that influences your physiology (top-down).
 • Your physiology affects your mood, and that influences your thoughts (bottom-up).
Now imagine you’re at work. You’re already overloaded with things to do, and an unexpected and urgent piece of work comes in. Your nervous system cannot make the distinction between physical threat and mental overload, so it responds as if the bear’s made a reappearance: your heart rate and breathing quicken as your body prepares for a fight, and once again, reasoning and critical thinking are inhibited.
Reduced executive function when under threat used to provide an evolutionary advantage to help keep you alive. It now presents a modern-day disadvantage, compromising your health, impairing your thinking, and potentially damaging your brain.
 If you regulate one part of this system, you influence the others, as the parts are inextricably linked. This offers three ways to manage stress, and consequently improve your brain fitness:

  1. Regulate your physiological state
    If you ever feel stressed or anxious, and feel your mental performance may be suffering try to do the following.
    Notice and regulate your breathing. Stressed breathing tends to be quicker and from your chest. Slow your breathing down and breathe from your stomach. How are you breathing now? That’s probably what you want.
    Practise meditation or mindfulness. One of the best ways to regulate your physiology over time is with meditation or mindfulness.
    Practise progressive relaxation. Try this next exercise right now. It will show you how to regulate your physiology.

 1. Get comfortable in a chair, with your feet flat on the floor and your hands in your lap, and close your eyes.
 2. Spend five minutes relaxing your whole body. Start by focusing your attention on your toes, and then consciously relax them. Some people like to tense the muscles first and then let them loosen. Once your toes are relaxed, relax your feet, ankles, calves, knees, thighs, and so on, all the way to the top of your head, and even your face.
 3. When you are done, in your own time, open your eyes.
By deliberately relaxing your muscles and slowing your breathing, you’ll lower your cortisol levels, activate your parasympathetic nervous system, and put your body into a state of rest and repair. If you do it regularly, you will improve your health, you will sleep better, and you’ll maintain greater access to your higher-order cognitions, such as reasoning and decision making.

2. Regulate your emotional state
You probably know some people who don’t cope at all well under pressure, and others that need stress to perform at their best. Everyone responds to stress differently, because we have varying degrees of emotional resourcefulness, or resilience.
 To increase your resilience and make it more likely that you’ll respond well to stress, do the following three things:
Make time for doing what you enjoy. If you feel positive, you are more likely to see stress as a challenge rather than a threat, and be able to convert pressure into elevated, rather than diminished, performance. To sustain your performance at work, you need to make time to have fun outside of it.
Write down the five things you enjoy doing the most, or that give you the most energy. Make more time for them. Book at least one date to reflect this into your calendar right now.
Develop your ‘locus of control’. If you feel in control, things are less stressful, because you become more resourceful. External conditions may be outside your control, but how you respond to things is within your control.
Write down the top five things, activities, or people that frustrate you, or drain you of energy. Challenge how you respond to them. How can you react in a way that affects you less?
Remember your purpose. You are more resilient when you feel you have a purpose, and more resourceful when you are making progress towards objectives you find meaningful.
If you feel stressed or you’re having a rough time, remind yourself of the reasons you’re doing what you’re doing.

3. Regulate your cognitive state
Finally, you can meditate every day and have unusually high resilience, but if you can’t manage your tasks and projects, your system will go back into stress due to cognitive overload. Managing your cognitive state is as important as any other stress intervention:
Do a brain dump once a week. One of the quickest and easiest ways to reduce cognitive overload, this will help you externalize all the things you need to do, and immediately put your brain into a more useful state.
Develop a working system that prevents overwhelm. An effective and stress-free working method.
Practise meditation or mindfulness.
For more depth on these techniques read, The Brain Book.