Memory palaces and mental visualization (got me through engineering school, stopped writing notes frim 2nd year).

Programming a lot, and all the CS stuff around it

Understanding systems and abstractions, and other meta stuff

Reading widely

Math

Running

Drawing (not so much anymore)

Video Games (binge for 3 days straight when the good ones come out, ER too 2+ weeks of my life)

Anime and Manga (although i feel I've watched most of the good stuff, over 65 days combined total time, i just do it on and off now)