In my experience most things which people call "mental problems" are caused by themselves. And the solution is to stop causing them, not to learn how to "manage" with them.
This is a subject where you don't need to know (intellectually), the experience is more important. Do you "know" joy better by experiencing it or by learning from a textbook or a school class?
https://www.youtube.com/watch?v=FzOv14fA-BI