Prior to lurking here and reading the excellent posts on rationality, I had never before considered eating a tomato. I decided that I didn't like them at a young age, and never revisited the belief. In the past, I figured it was my business and it wasn't hurting anyone if I decided to avoid tomatoes. Now, I understand that it was an arbitrary preference, that the taste is non-offensive (I may grow to like them), and that they are rich in lycopene (which may be good for you, but almost certainly isn't bad). In short, I changed a belief I never before thought necessary to revisit. So far, so good.