The problem is the mental fatigue / penalty as a consequence of not working in things you are interested in. I work @FAANG, for the stuff that I am actually in

The problem is the mental fatigue / penalty as a consequence of not working in things you are interested in. I work @FAANG, for the stuff that I am actually interested in, I found myself casually hitting 60 hours per week without even thinking about it, plus M hours at home working on adjacent stuff / ideas. I worked here during my last semester of uni when I finished my thesis, and I was fine because I was doing genuinely interesting stuff. However, the mental exhaustion that comes with context switches or dealing with uninteresting and mundane stuff that still involve effort makes it very difficult for me to actually spend time writing code or doing something productive after / outside.