Do you ever get a song stuck in your head? The tune comes back to you, over and over again. Even when you do not want to think about that song, it keeps coming back. It nags you. Living with alcohol, tobacco, and other drugs can be like that. You start smoking tobacco, and then one day when you wake up, the first thought that comes to mind is, "I need a smoke." You cannot make the thought go away. Even when you do not want to think about cigarettes, the idea keeps coming back. It nags you and nags you. For most tobacco smokers, that nagging feeling is followed by getting up and finding a cigarette, lighting it up, and smoking it. Ask a smoker: "If you were to stop smoking, which cigarette of the day would be the hardest to give up?" Most of the time...