I'm an ex-smoker - bloody hard to give it up, but I've been stopped somewhere over two years, now, I think.
However, it's something I've been really tempted to restart - it's such an insidious habit that becomes a part of you - I think Chandler on Friends once describd it best by saying something on the lines of "Think of it as what has always been missing from your hand".
Doubt I'll restart, because it could be really bad on the asthma and my lungs are pretty clear now. Besides, we demonised it to the children, so the eldest would be especially horrified if I started.
The one thing you really have to watch qhwn quitting is weight gain - smoking suppresses your appetite, but once you quite, it's easy to want to snack all the time.
Anyway, here's an ex-smoker hoping to stay that way.