I personaly only put 20% effort into 80% of everything. Getting in the Pain region of "how hard you try" should only be done when you know the effort is worth it.
It seems that getting into pain is not the problem. Rather contrary, i think knowing that the pain was worth it and one has achieved something incredible is fundametaly positive. At least for me.
The problem seem, that people are constantly in pain for things they shouldnt be. Family, kids, jobs, hobbies, looking attractive, studying for best grades,... they want to reach 100% in all areas. Which is per definition not possible when your scale are the performances of others.
Putting 20% effort into as many areas in live as possible, with selected bursts of maximum effort, seem to be at least for me the better strategy to be happy.
for me, its even more Slack for the mind. And i would have initially associated the benefits with creativity.
Im a CEO and have lots on my mind. i can use up all of my worktime to put out fires,... at home 3 kids, and lots of hobbies. So my mind is not allowed to rest it seem.
I usually had the most creative or problem solving revelations when i was traveling in my car for hours. I recently started with audiobooks while traveling. This affected me heavily, creativity and revelations reduced drastically. I also noticed this, when i switched from scientific work on a university to a business job. Time to think, reflect can only be found in slack time for me.
Same applies to workforce, if they have no slack i receive 0 suggestions for improvements outside their job. As soon as they are little bit idle, they start to think outside their box it seems.
Just wanted to share this, as thats the first thing i was thinking about but i would have put it differently.