Although I'd given up for a week or 2 before I joined, it took me a long time to get to that point.
This is what worked for me. You might find something useful:
1. I read up on the stages of alcoholism. You can Google it, and it's not pretty.
2. I spoke to my doctor about it. It didn't work straight away, but it was great to check in after I'd given up, and have him praise me!
3. I began to see it affecting my weight and friendships.
4. There was an ad on telly with a professor saying that drinking above the limit was as bad as smoking for cancer risk. I've always been judgemental of smokers so I gave up to prove I could do it.
5. A couple of drinkers I knew died of throat cancer - a horrible way to die.
All this added up over time until I found the will to quit. It wasn't hard once I'd made up my mind, and I didn't relapse because it was such a relief not to worry about it any more.