My dad smokes and the smell of it makes me utterly sick. Not only that, but female smokers look even tackier than male smokers do, and I don't really want to embarrass myself like that... I'd be ashamed to see people I know smoking and would probably pretend not to know them until they chucked that cancerstick away.
Call it childish, but I don't need anymore health difficulties.

The smell and second hand smoking is disgusting, and death via smoking runs down both sides of my family. (Mothers' mum, fathers' brother, fathers' sister is currently dying due to smoking.)