I will tell you something that is possible to shock you: is Ok to smoke. As long as you are Ok with this habit and you don’t judge yourself it is fine you are a smoker. I know many smokers that had a long and happy life. Many poets or intelligent people was smokers and die smokers. Smoking is not bad as long you are ok with this.
But if you want to quit you had to know that your are the one who decide. Nobody will tell you to quit. Not books, not psychotherapist , not family, friends or partner. You and just you decide if you quit or not. The judgment comes from within you, you decide.
When you have this decision, you will quit.
If you have been quit smoking for a few days, do not boast. Keep secret, at least for a while.
Replaces the habit with something else. A fruit or water is the best substitute, besides this is healthy.
Make sport. The body, after exercise, releases a hormone like that released from the cigarette or other substance you are addicted to.
Do not give up. Thomas Edison made over 10,000 attempts before to discover the light.
Even if you did not succeed for the hundredth time, try one more time!