Now, I think it's probably because I have to cut back or risk a fatigue crash. Since I can't contribute as much, I want everyone to do less.
Then I won't feel like such a freeloader, benefitting from everyone else's hard work while doing so little myself.
I've not really acknowledged this to myself, let alone talked to others about it.
It seemed like if I just stepped back without making a big deal of it, no-one would mind much.