In my experience, this is most helpful in early sobriety - it took me a few months to stop having daily cravings. So, I'd always tell myself at the start of the day I wasn't going to drink "that day" and then, when the cravings inevitably hit, I'd remind myself "not today." Now - after some 3 years sober - I say "I don't drink" or that "alcohol is not part of my life." Not just today, every day. Still, on the more rare occasions when a craving hits, I can fall back on "not today."