Well My mum was an alcoholic who smoked and drank during pregnancy, and it never did me any har- URK!
Sorry, just a minor heart attack.
My doctor genuinely proclaimed me "cured" of asthma not long after I took up smoking (from GCSE stress, no less).
Getting back to seriousity, there's plenty of time for experimenting with intoxicants (legal or otherwise) when you are older. Or not, as the case may be. Whatever you do, just be sure that if you do decide to try some form of mind altering substance, it's because
you want to try it, not because of peer pressure.
While my serious hat is on, if you ever have any questions about such things, feel free to shoot me a PM (probably shouldn't be going in to too many details on a public forum
)I can tell you from experience (personal or seen friends go through it) which ones to avoid and which ones are harmless.
EDIT TO ADD: the worst addiction I have ever seen a friend go through?....... Gambling. Make of that what you will.
.... Aaaanyway, happy thoughts everybody!