I have a well defined mission in my life, so when acquaintances ask me to do something, my default answer is generally no (unlikely when my wife asks me to do something, where my defat answer is yes).
Unfortunately, when some people are persistent enough, a yes occasionally slips out.
This happened to me recently. I said yes to a project that, although it is something which needs to be done and something which I am good at doing, I knew would cause me severe mental anguish to do. (i.e. some people simply shouldn’t do work in some domains.)
Yet here I am at week’s end, with this project finished. I am not just angry at the person who kept pressuring me to do this project, but I am a thousand-fold more angry at myself for allowing it to happen.
There is a reason I have a default answer of no, and I forget this at my peril.