“Happiness comes from solving problems. The keyword here is "solving". If you're avoiding your problems or feel like you don't have any problems, then you're going to make yourself miserable. If you feel like you have problems that you can't solve, you will likewise make yourself miserable. The secret sauce here is in the solving of the problems, not in not having problems in the first place.
Happiness is a constant work in-progress, because solving problems is a constant work in-progress - the solutions to today's problems will lay the foundation for tomorrow's problems and so on. True happiness occurs only when you find the problems you enjoy having and enjoy solving.”