It's a lot of work. Solving problems over and over again.
There is a concept called retrieval practice, which really helps. Essentially you want to practice solving problems without looking back at the explanation on how to solve the problem. The more you pull the information out of memory the longer you'll remember it.
Maybe you guys are just godly. I couldn’t imagine why my math teachers could have done what they have done. They are too godly. English teachers are godly, too. They are more of the subtle kind.