1. I've always had a problem. Got drunk the first time I drank, at 15. I would then get drunk almost every time I drank after that. After age 35 or so I noticed that I was drinking more often. By my mid-40s, this was pretty much every day.
2. I gave up at 52.
3, Coming round on the bathroom floor covered in blood with no idea at all how I got there - then registering the pain and concern on my partner's face, that's what stopped me. The way I feel physically and, more importantly, psychologically, is what motivates me to stay stopped.