Running I find is a good start?
I've never done drugs, but the first step is understanding why you SHOULD stop.
Once you do that, you wont have such a urge to do them.
Whether it's Weed, LSD, Coke (lord i hope not), or E. I think you should sit down and think over what you've been doing.
Maybe you'll find a understanding of what exactly you can do to distract your self.