So why in the fight between willpower and addiction, it is the addiction which wins most of the time? The answer is simple, cravings are short term, gratification instantaneous while the benefits of quitting are long term and imperceptible. So how do we win this battle? By relying on the short benefits of quitting, while recognizing that while cravings are powerful, they go down very quickly. They are pretty much gone in about a month. So if you can hold on for a month, your chances of winning increases dramatically.
So how do we focus on the short term gain? This is mostly on the healthy living. Whether you are quitting smoking or drinking, it immediately leads to very healthy improvements in your lifestyle. You sleep better, you get more energy. Convert that into activities, cycling, swimming and you will feel a lot more cheerful. You can fight negative thought more effectively. If you are quitting drinking, then you are getting back your wit. Use it to something cerebral and you get an immediate return. Read a book, play chess.
For myself, quitting drinking brings enormous benefits. My wit is all I have. I do not have a great physique, I have no social skill, I do not enjoy the company of others that much, I do not watch TV or sports. I live my life through my brain. I have a house full of books and a computer full of movies. I can enjoy them much better if I keep my wit and use my brain, instead of losing it every free evening I get. Then why it is still so hard to give up! Why indeed :)