Never took time to learn group theory that underlies Rubik's cube, but spent this morning trying to figure out how to solve in semi-math way it with a friend.
Having 2×2 lying around was super helpful, we did it first and almost cracked 3×3 afterwards (I had to run).
Another thing I wanted to learn more about from semi-theoretical pov is juggling notation. But given that I can't even hold a relatively small number of things without them falling down almost immediately will probably get in a way.
Tired: I can't even hold stuff, juggling is not for me
Wired: juggling is precisely dropping, catching, and dropping again before the other things fall down