Not driving. Like some of the best people I know, Andrew Sullivan doesn't drive--can't drive. Not driving keeps you from doing some things, but the limitation shapes your life in many positive ways, as AS notes. Personally, I love to drive, but once I lived for a semester in Boston without my car, and not having the car made life better in many ways. Oh, and "once" I lived in New York City for 10 years without a car, and it was great. Not driving increases the likelihood that you will live somewhere interesting.