Although I strongly agree with the mantra of no pain no gain, the applicable example here of pushing yourself to do more than 40% of your potential pull-ups is far too simple of an anecdote to address the complexity of ruts that many people find themselves in.
Many of the things worth doing in life involve more actions than doing a pull up. You don’t always know which actions you should take to get closer to your objective. Your objective may also often spans over a period of time, and there are often external dependencies i.e. opening and closing hours, other people, supply and demand. There is inevitably going to be idle time when you have to wait. Waiting leads to distractions, and the key here is to figure out what to do with your waiting time. If it’s just about doing pull ups, you can simply jump into action and push yourself past your 40%. But what if your goal involves more than one muscle group and building muscle memory in one area of your body is actually contributing to a bad habit that detracts from your goal? Jumping into action is sometimes a mistake. Not taking action is also a mistake. I don’t think we can escape from the painstaking process of thinking long and hard but not too long and hard. I think it’s important for people to understand that when you commit to an action, carry it to 100%. But when you find yourself faced with idle time, and you will, because of physical limits and external limits, take this time to think long and hard about the next action you commit to. Making a good decision takes time and perspective.
I am also conflicted about your thoughts on living in the moment. If you don’t live in the moment, then you are either living in the past or living in the future. The past or the future are just thoughts, and they are definitely not “real and lasting”. In fact, the only time that is real is the present. You will never find true happiness because it is simply an idea in the future. True happiness is the endless pursuit of the idea. If you fill that pursuit with momentary displeasures, then it will only lead to a miserable life. I think it’s extremely important to live in the moment, to enjoy the momentary pleasures, and tolerate the momentary displeasures. They are just passing moments of life that don’t deserve connotations. They simply need to be observed.