It is always sort of amazing how quickly you can make the decision to drink out the blue on a dime and not reconsider.
I don't attend AA, although I should, but something that has helped me recently has been their "just put it off till tommorrow" philosophy. You've probably no doubt read it, but they say something to the effect of "we neither deny nor give in to the craving, but just merely put it off till tommorrow". And tommorrow never comes. Or by just giving yourself 30 mins or so, the craving passes, and you reconsider. It's helped me to think of it in that light recently. Good luck.