In the almost 5 years I've been sober, I can count on one hand the times I've been asked "why?" when I say I don't drink. At first I felt like I needed to spill my story and really justify it, eventually I just found a few quips to say like "I drank my share long ago" or "I drank too much/liked it too much, so now I don't" or just "it's healthier for me if I don't" if it's close friends or something, I'm comfortable enough with my past and my sobriety to open like that but I really feel it's never necessary. A lot of people don't drink. I'm not a huge fan of lying about it, I get the temptation but you're right, it doesn't feel good. People who ask why really don't want to know that it's because you're an alcoholic and all the judgment or whatever that goes on with that, that's why "I used to, now I don't" generally gives them the picture, but I never feel I owe anyone an explanation they really don't want to hear anyway.