It hasn’t been nearly so long for me, but I’ve managed to hold on to much of the math I’ve learned by re-proving theorems I’d learned and solving problems in my

It hasn’t been nearly so long for me, but I’ve managed to hold on to much of the math I’ve learned by re-proving theorems I’d learned and solving problems in my head during downtime, while doing household chores, and while falling asleep. Another benefit is that I am almost never bored since there’s always more math to do.