 If I'm overweight and I want to have a healthier body, then I can't eat like I used to eat. My preference is to eat like I used to eat. My priority, however, is to become a healthier me. I have to override my preference with the power of my new priority. The new priority then becomes a new preference. That's done by having one desire that is stronger than the other desire. If my desire to have a healthier me...