I live 115 miles away from the nearest fast food place. That nips it in the bud pretty quick!
Seriously, though, I didn't eat that kind of stuff before I moved, either. I think in order to make this work, you have to develop the attitude that some foods are for other people. Don't think, "I can't have fast food;" think, "I don't eat fast food." It might help to be snobby. Most of that stuff really doesn't taste that good. You can make better-tasting, better-quality food at home. In fact, the difference for things like baked goods is so huge that once you start cooking for yourself, you probably won't even be very tempted. I look at things like packaged cookies and just automatically think, "I should make something like that." I never even really consider buying it any more. (And then I go home and DON'T make it because I keep putting it off. Food snobbery and procrastination are a powerful combination!)