Teaching a beginner is the fastest way to see your skill with fresh eyes again.

Most of what you are good at has gone automatic, which means you can do it and no longer see it. A beginner asks the question underneath the step you stopped noticing, and suddenly you have to look at your own habit and decide whether it is actually correct. That is why teaching finds holes that practice never does. It also returns the thing to you as strange and interesting instead of routine.

Teach one small piece of what you do to somebody who is starting. Keep track of the question you could not answer cleanly, because that is your next thing to learn.