I am curious on how you Math and physics gurus retain the amount of math you know. I have this horrible habit of learning a mathematical or physics concept and then forgetting it months later. It never truly lasts long if I don't use it.

I have some math books lying around, and I usually try to learn from them whenever I can. I just don't want to waste my time reading and doing problems when I'm just going to forget it in a couple of weeks.

I just want to know what the secret is. Is it a matter of practicing math everyday? If yes, then how do you know which subject to practice on?

Would appreciate some input.