Let me explain: When I tell patients to stop smoking, they know exactly what to do, namely to stop putting a cigarette in their mouth and inhaling its smoke. That's a behaviour they can change. When they stop smoking they have "successfully" changed a behaviour -- that's behaviour change, end of story.
There's a gnawing in my stomach, as if a string of spikes is gently lodged against my gut. It's this that prevents me from eating; the stomach pains. In fact, a Big Mac Meal is the first thing eaten since waking up yesterday morning. I'm at six cigarettes. Usually by this point, I'd have smoked about 15.
Quitting smoking is like breaking up with a lousy girlfriend who you've been dating for a long, long time. Sure she hurts you at times, she puts you in a bad mood, she's not always at hand when she ought to be. But it doesn't matter, because like with everything, once enough time elapses, a dependency is formed.