For me, abstract thought comes best when doing abstract things. Particularly reading, camping, cycling, playing/listening to music. As somebody who spends way t

For me, abstract thought comes best when doing abstract things. Particularly reading, camping, cycling, playing/listening to music. As somebody who spends way to much time in front of a computer monitor, I find that anything that takes me away from screens for a few days is really beneficial for mentally tackling big problems. A great test of how well you understand a (mathematical) concept, is if you can visualise and reason about it when you are away from a desk and doing something else. That said- you can never know all the stuff you want to know, so dont stress about it :)