I quit after I started to experience shooting pain in my lungs and heart. I was scared into stopping really. After I had a cigarette my lungs felt like they were on fire. That's all the motivation I needed. My doctor took all kinds of tests and said it was the cigarettes.
The pain stopped after I quit smoking and I never had any cravings for a cigarette since.
You can do it, It's all in your mindset; If you want it, it'll be the easiest thing you have ever done, trust me.
Good luck to you!