I was always really impressed with a lad I knew at university, who simply stopped in his second year. When I asked him why, he said with great candour "because it makes me a c**t". There was no one defining incident, or health worry and he didn't feel any sort of dependancy, he simply decided that he didn't like the person he became after booze and stopped. On the flipside, I know someone who is really unpleasant after a drink. However, because she doesn't drink every day and can go for weeks without a drop she refuses to accept that she has an alcohol problem. She just seems to accept it as the way things are, even as she is phoning people to apologise the next day.