I knocked it on the head because the hangover was no longer worth it.
it wasn't really a conscious decision, I just realized that I was no longer choosing to have a drink in all the old situations. Suddenly it was a few weeks, then a few months.
I will have a drink or two on occasion, but I realized every time I get drunk, it is at the expense of too many other things I enjoy doing.
only downside is meeting friends on a sesh and discovering they are all babbling morons
weed is an entirely different story