Just learn more math and you'll get all the abstract thinking "workout" you can handle and then some. But what is your goal? Is this just as a form of exercise

Just learn more math and you'll get all the abstract thinking "workout" you can handle and then some. But what is your goal? Is this just as a form of exercise? If so, I recommend going through (really understanding) Godel's Incompleteness Theorem(s). In my opinion, it's very hard but it is something that's doable without an insane level of prerequisites depending on how you approach it. It's also quite interesting and one of capstones of the 20th century, but don't bring it up at cocktail parties.