Exercise is my number one coping tool. Whenever I have to stop, my mental state noticeably drops. I use to train an a MMA gym 3-4 times a week, and also went to a normal gym 2-4 times a week or would run outside depending on the weather. Right now, I can't fight because of a shoulder injury, and at first I had to totally stop exercising for about a month and I mentally crashed. I recently got the okay to start light exercise again, and already I feel better.

Aside from the runner's high, when I started seriously working out again about a year ago, I just naturally stopped smoking and found myself not craving it. I know you're attempting to quit right now, and I'd say that running is one of your best tools to quit. Once your body starts getting into better shape, you'll physically not want to smoke even if you still want to mentally. Furthermore, I just found myself at the point where I had to pick between smoking and better athletic performance and that's what kept me off of cigarettes.

Keep training and good luck. Hurts like eff at first, but your lungs will get better.