I used to drink fairly regularly. I started mainly to fit in, and I continued because I actually developed a taste for beer - which is equal parts a blessing and a curse. I got drunk a few times, but never to excess because despite how much I enjoyed it, I could never fit more that three or four cans into me. Another blessing/curse.
I don't drink that often anymore though, but there's no real reason for that. I just don't feel the urge to anymore I suppose. Certainly does no harm to the bank account at least.
As for drugs... I don't smoke tobacco, as I'm pretty big into cardiovascular health, and have been for a few years. I don't mean to sound big headed, but my fitness is a point of pride for me. I really don't like the idea of damaging my lungs.
That said, I have smoked weed twice. The first time was out of curiosity, but apart from a few fits of spluttering and gagging, it didn't do much for me. My friend informed me that that's normal for your first time, because your body has yet to build up a reaction to it. I don't know how true that is, but my second time smoking wasn't any different, except I could handle my coughing a bit better. I recall thinking that I might've just got a "defective" batch but my friends got high off the same stuff just fine.
And that was it really. I didn't necessarily give up on it, but I just wasn't arsed trying it again. That was a few years ago now, and I don't feel any different. I might go back to it someday, but it wouldn't bother me if I live the rest of my life without ever seeing weed again.