Instead of trying to control the craving or stop thinking about cigarettes, you have your brain evaluate the "should I smoke right now?" question with the answer _no_. Once I did that, I found quitting smoking surprisingly easy. I still think about it quite a bit, but so far I haven't strayed from the correct answer even a little bit.
Regular exercise right at the beginning will help you ride out the initial physical cravings. Within a week your lungs feel much better and you're way more alert etc etc so the virtuous loop is in place and that's where I am and so far it feels pretty good.