I don't smoke because I didn't grow up in the sixties or seventies; I grew up in a time where everybody knew better than to start such a silly habit lol.
As for drinking, I made the executive decision not to start. If you never start, you'll miss it, right? I also fear I have an addictive personality, so I find it's just better never to open that can of worms. Also it tastes terrible and I object to the mentality I see in people my age all around me; they started drinking when they were 15 or 16 and now they start to feel like there's no social gathering that should be without alcohol. It's almost as though they need alcohol now, in order to have fun. I just don't want to be like that.