The hobby you picked up for fun just taught you how you learn best. Pay attention to that.

Nobody supervises a hobby, so how you went about it is an honest record of how you actually learn: by watching, by taking things apart, by repeating one small piece, by talking to people who already do it. That method worked precisely because you chose it with no system imposed on you. The same approach is available in the subjects you find hard, where you have been using somebody else’s.

Think about how you got good at the thing you do for fun and write down the first three steps you took. Apply that pattern to whatever is giving you trouble.