I have been smoke free for over 2 years and 5 months now. I find that the key to long term success really has to do with seeing yourself in a different light. The day I quit I made the decision that smoking was no longer acceptable in my life, and since then how I view myself has changed from that of a smoker to that of a quitter to that of someone who is in control.
I hated not being in control of my actions and being controlled by nicotine and cigarettes. It made me feel weak. That was one of the driving forces behind my quit.
For each person it is different and personal, though. I took me one morning to quit, after years of attempts. I hope that knowledge helps you out there who have tried and failed before to keep at it. It will happen eventually, just don't give up.
Good luck getting to tomorrow everyone