For a considerable amount of time after I quit smoking, I kept carrying a pack of cigarettes with me. This helped me in two ways.
First, when i felt like i really need a cigarette, i would put one in my mouth and pretend to be smoking it without actually lighting it.
Second, always having a cigarette available on me kept reminding me that I'm not smoking not because I cant, but because I don't want to.
Before I quit smoking i have smoked for 12 years. I haven't smoked for almost two years now.
I know its not an easy struggle. Good luck with it:)