Went out to my car one day and found that the brakes had gone out, I had to drive home with the emergency brake. I had money to fix it, but I was really annoyed that my functioning was dependent on my car. So I went and bought a bike and figured I should get in shape with it, just in case the car broke for good I would be ready to get everywhere. And then I realized that what was really keeping me from biking was that I lived at the bottom of a mile long hill and I smoked a pack of cigarettes every day, so I had to quit smoking.
Quitting smoking didn't work out all that well at first, but I found if I biked a lot, it relieved the nervous energy that would cause cravings, so I biked more and more. It worked and I haven't smoked in a year.
As a result, my car stays parked and I bike just about everywhere. The only time I drive is when I go out of town or way across the city. I'm pretty happy about it.