The hubbie used to smoke. When we got together, I informed him he gets smoke or me, and he put himself on a plan to quit and stuck to it. He still says he made the right decision, many years later. If he smokes I can smell it even days afterward, but it is one every six months, and he always eventually tells me about them, so in my opinion he kept his promise of quitting.

I recommend a sympathetic friend or quitting partner as the most effective method.