I drank briefly for a year or so during the start in college, but now I so rarely do that it basically counts as not drinking. Perhaps a glass of wine or a shot of something once every 6 to 12 months. The biggest reason would be that it doesn't feel good. Even the smoothest drinks burn a bit to the inexperienced, and I hangovers are no fun. The vast majority of drinks though I simply don't like. Like I said, there's an occasional drink that I may enjoy, but they are very rare, and in small amounts.
Another reason is my girlfriend doesn't drink. Alcoholism runs in the family, so she won't even try it. When you aren't hanging around alcohol, you're a lot less likely to drink it. No fun being the only one buzzed or drunk.
And lastly it saves me a lot of money when I go out, haha.