This one is going to be fun, I can tell you right now.
I don't drink. I'm not permitted to. Over the past year, I've had 2 bouts of kidney stones formed from high levels of uric acid in my kidneys. Because of this, I've been put on a specific diet of food to help keep those levels down. One of the things to go, was any kind of alcohol, as it is apparently bad in terms of uric acid. But I should mention, that I never really drank before then. It's a control thing. I don't like not having control over my body.
Drugs. I detest them. Illegal ones that is. Same issue as with booze. I'm just not the type of person who likes being unable to control my actions. It probably sounds stupid, but it's just who I am. I like that feeling of knowing that I'm not going to wake up tomorrow and wonder if something I can't remember having done the night before will be all over facebook, or that I did something incredibly stupid that I wouldn't have done if I was in complete possession of my faculties.