Be a 2.7 Percenter
I ran across an old article that can be disturbing in some ways. According to this article, only 2.7 percent of the U.S. population does four key things to maintain a healthy lifestyle.
Exercising and eating healthy will take care of the third item on that list, but the last item is the hardest. I've never been a smoker, but I watched my parents struggle with it for years after they quit, so I can only imagine how hard it is to stop. The best advice I heard has to do with building new habits around the situations where you used to smoke.
The funny thing is, maintaining moderate exercise and eating healthy are also habits, and my system is all about building using mental manipulation tools to build new habits.