What do you do when you're low on mental energy? I have had trouble thinking of anything productive to do when my brain seems to need a break from hard thinking.
A rather belated response, but hopefully still relevant: consider exploring fields of interest to you that are sufficiently different from compsci to give your brain a break while still being productive?
To explain by means of an example: I happen to have a strong interest in both historical philology and theoretical physics, and I've actively leveraged this to my advantage in that when my brain is fed up of thinking about conundrums of translation in Old Norse poetry, I'll switch gears completely and crack open a textbook on, say, subatomic physics or Lie ...
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.