Two essential things to happen to a person to make him older.

Disappointment in fantasies, omnipotence, limitlessness, infinity, absolute choice and the ability to please everyone. Humility and acceptance of the fact that you're not hanging in the air and can't be cooler than everyone else. Accepting the way things are, and the presence of other people in your life. And the sooner that happens, the more accessible simple human happiness is. Not the kind that requires conquering the universe, but the kind that can be made with your hands, and achieved by simple actions. Not comprehensive, but finite, concrete and simple enough.