I don't drink either, but I'm perfectly happy to answer "It's unhealthy and I don't like it" when people ask me why. Of course, I also try to avoid social interaction, so if this is a rude response it might not be as useful for others.
That's akin to declining chocolate from a fat person by saying "no thanks, it makes me fat". I don't drink for medical reasons , although I used to in my twenties. I don't feel the pressure to drink, but understand why some people feel they need a reason. Saying "I don't feel like it" should be sufficient for most people
