Nature has built a surge capacity within us to deal with emergencies, working as if everyday is an emergency results in blowing the fuse on that surge capacity.
Imagine you lived in the hunter-gatherer world and you were confronted by a beast which is about to attack you. If you feel you can overwhelm the beast, you would prepare to fight it, or you would prepare to run from it. Say you run from it and escape, rarely would you go looking for the next beast to run from.
In that moment of fight or flight, you decide what you want to do, the adrenalin kicks in and you operate on surge capacity. It takes a lot out of you and you are left with a story to tell at the end.
I often find that people remember the times that they struggled at work to pull off what they considered impossible. Rarely have I come across anyone reminiscing about that week when they went to work only to play solitaire the entire week.
In a capitalistic society where everything is about growth, you end up looking for the next impossible once you have delivered the impossible. That is how your career will progress; how you will make more money; how you would hopefully get to live the good life. Invariably you build a life where you are always operating on surge capacity, leading to burnout.
If you took a two-week sick leave; how would you feel about extending it another week? We have built a world where we feel guilty and ashamed about even being sick!
Nobody can constantly operate at surge capacity. If somebody is constantly operating at surge capacity, is that even the good life for which one threw themselves into the rat race?
Always keep a track of when you are being asked to do a lot more than you would like to and know when and where to draw a line.