Because you don't think as clearly anymore, you can't have as much fun anymore, your sense aren't as good anymore. Shit, you can't go to a club and flirt with 20-something hot chicks, ok? Weed and alcohol aren't much fun anymore. Your idea of fun is actually borin*g and you don't even know it because you have difficulty grasping half the stuff that's going around you. You are just old. In pain. Slow. Afraid. SUCKS!