Quitting is hard
I disagree! Quitting is easy. I've done it at least a hundred times!

Seriously, I have not had a cigarette for 2-1/2 years. This time it's sticking. And the reason why is just what Catland says:

I think though, that the mental part of it is most important. You have to QUIT smoking - you can't delude yourself into "quitting" smoking. Either you are a smoker or you are not. The people that I've seen be the most successful are the ones who quit and don't look back. They don't bum a drag or a smoke from a friend or just cut down to one or two a day.
Once I said NO MORE NO MORE EVER! I was on the road to being smoke-free.

Laura, some people have a really, really, difficult time quitting because for them the addiction is part of their psyche...the physical part isn't the problem, it's the mental. It took at least a year for me to stop thinking about "having just one cigarette" especially when I was under stress.

When you're ready, put down that cigarette and say NO MORE EVER and mean it! NO cheating! No bumming! EVER!

Good luck to you. Sorry I can't help with the weight gain issue except to agree with the others that exercise is your best option.