Why does MISERY teach more lessons than JOY?
Joy makes a man to enjoy life in all ways – food, shelter, entertainment, friends, etc etc. and has less time and favourable mind to analyze, infer and conclude logically. Also there is no motivation for that. In misery, almost isolated and worried, mind will always be engaged in finding ways to overcome it and repeated failure to achieve the goal teaches him many lessons responsible for bad periods and methods for improvement.