I had to finish up my PhD while already working at a FAANG. My professor would keep stacking more stuff that he wanted to have in my thesis. It was a horrible time and I think I was very close to a burnout.

One thing that I later noticed was that I e.g. couldn't enjoy any music anymore. I always used to be able to be absolutely amazed by some tracks and dance to it at home - but during that time there was just nothing.