Pretend you or someone you know has a bad habit. A big bad monkey on your back. How did it get there? How did it start? Probably a combination of three things; emotions, authority figures, and repetition.
We need a person to use for our example. Let's use you, when you were 10 to 14 years old. For the sake of discussion, let's use the smoking habit. Ok?
So when you were around that age I think we can safely assume you were learning about life and how you fit into it. If you were like most kids, you weren't as confident about yourself as you would be later in life.
Kids that age sometimes feel self-conscious, dependant on others, powerless, not good enough, or??. We'll call this feeling "bad". This is not saying you felt miserable, but maybe didn't feel "good" as you thought you should feel? Did you feel as "good" as you thought other people felt?
Feeling like that would lead you to wanting to feel better, or, as good as everyone else. What ways does your mind see to do this?? That matters upon what learning situations you've been exposed to.
Experiences that teach you smoking is strong, capable, tough, independent, self-assured, unique, and feels "good". Experiences that involve emotions, authority figures and repetition. Of course advertisements do this, so do parents and family members. Are these experiences repeated? Of course.
This would create a desire (craving) in you to do this thing. A belief that smoking is what your life is missing. And not just in a "knowing" way, but a "feeling" way as well, which is much more powerful.
Eventually you smoked your first cigarette, and DID feel better, sort of. You weren't too good at smoking the first time. You had to practice to get good at it. And you did.
Life goes on and you continue practicing your smoking habit. Reinforcing the existing cravings and creating new ones. Like branches on the tree of the first craving.
People that have tried to quit smoking have spent a lot of time analyzing their habit, fighting themselves for control of cravings. But, you didn't learn the smoking habit with the thinking and analyzing part of your mind, so why try to use that part of your mind to change the habit?
It is common sense to quit smoking using the same elements that created the habit. A "hypnotized" mind, along with emotions, authority figures and repetition. These are the elements of modern hypnosis.