I quit after 15 or so years ... its easy at the beginning, the real problems start after a few weeks
For me it was the hardest about 2 months after I quit, I felt strong urge to smoke. But its all in the head, if you really want to quit, you can do it. Its almost 2 years since I quit and I am still clean (only smoke once once my wifes BD and I was wasted like a mofo). But I still feel the urge to light one from time to time