Originally Posted by
jazzfish 
We live in strange times when if someone doesn't drink, we think they are an alcoholic.
Seriously, just say "no, thanks." If they push it, look them straight in the eyes and repeat, "no."
I spent far too much time in the previous sober periods trying to come up with good excuses, usually linked to so medical condition/test or upcoming surgery along with a health goal I had set and a temporary break. It all got too complicated. Straightforward and unapologetic is the best bet.
I think the difference is when you are trying to not succumb to friends and acquaintances where of course a no or ignoring them will do the trick and when you might be in a business situation when you are trying to schmooze a client or not to let your boss and colleagues suspect that you have a problem. Many a business deal happens after hours so telling the person you are with that you do not want to partake when they are having a great time can be a delicate situation. Then you might need the abilities of a politician. Practice the art of being cagey.