Great topic, Mags.
Being only three weeks in, I still bump in to people who will say, "Let's go grab a beer." It's hard to say, "No thanks, I don't drink" in those situations so I've just been telling them that I'm on a health kick, trying to lose some weight. Once I even went to the bar (couldn't get out of it, really) and had a club soda using the same excuse.
I'm looking forward to the day when I have so much time that it's easy to just say, "No thanks" or "Club soda, please" without having to explain myself.