I think Phillykid has the right idea; people are usually influenced by actions, not words. If your friends really are that important to you, what've you got to lose by showing them you've got your act together and the smoking is just a recreational passtime? I mean play down the illusion that it's harmful to you; keep your grades up if you're in school, take better care of yourself, be the kind of person your friends enjoy being around, and so on. It's the stereotypes that make them think the way they do, probably a lot more than personal experience. See if you can figure out what the negative aspects are that they percieve in you as a recreational user, and try to break out of the patterns they think are harmful. As long as you're honest about it, I mean. If you're trying to decieve them, they'll probably know it, even if you think you're convincing enough to pull it off.
You may even find out that working on yourself to become a better or more agreeable person is worth the trouble, stranger things have happened.
Hope some of this made sense.
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