I used to smoke, quite a lot actually, pack a day. And then, after a week of partying, I woke up with no voice! I freaked out completely! Calmed down, told myself that I'm better than that and threw those 5 fags left in the pack.
So, unfortunately, I needed to go through a kind of a trauma to learn my lesson, which is terrible because it proves the fact that adults learn only by going through one. And fortunately for me, that happened at a right time (about 9 years ago) and now I'm grateful for the "experience".
To sum things up - party a lot, lose your voice, freak out, quit smoking.