The mental gymnastics our minds do are actually quite funny. It helps to look at it, say these things outload, and have a laugh at your own mind games.
For example, I had a dream that I was smoking and enjoying it. However, I quit because I wasn't enjoying it. The only thing it was really doing for me is increasing my heart rate, making it harder for me to breathe, and the only thing I could think of was, "When will I get my next one???" (I was becoming a chain smoker because I was simply an addict to it.) I don't remember enjoying it and that is why I quit. If I want to increase my heart rate and make it hard for me to breathe all I have to do is go for a run, or, a wobbly jog (I am not exactly the picture of fitness lol).
And que the picture of Simba from The Lion King watching Mufasa (his father) fade away in a cloud saying, "Remember, Remember meee." Remember the reasons you quit. The mind can and will play tricks on you. The best thing I have found to do is remember why I quit, and have a laugh at what mental gymnastics my own brain did.
The only thing worth missing is taking breaks, but you can easily do that without having to smoke. Just take a break, go outside, or listen to some relaxing music for 3-5 min. I like Native American Flute Music on Pandora. It is way more relaxing than cigarettes!