Actually realizing that I need my liver and that I would have had a much shorter life if I kept drinking.
The challenge of doing this for myself was also very important to me - to test my strength... even if it was only 10 minutes - 20 minutes - 1 hour - 1 day of my time.
There's a lot more -- many things happen. You find yourself wanting to focus on ANYTHING other than even thinking about Alcohol to get it out of your mind. Like put that thought in a box and dare not open it.