Actually, I have two:
I draw too much and clean it up too little. I, like most people played with crayons and those stupid watercolor paints kindergarten teachers gave you only because they clean up pretty easy. I just didn’t stop. I’ll doodle and create all day long.
Unfortunetly it leaves alot of ungodly mess and trash I don’t have time for.
Listening to music.
Except if I find a new song or something, I’ll listen to the same song, over and over again. It drives the people around me crazy. I probably started doing that about three or four years ago. I blame iTunes and repeat item.