The February issue of Fast Company has a piece on the role visualizing plays in goal achievement. If you found the two posts on Beliefs, Wishes and Goals useful, then Make Goals Not Resolutions may be worth a look. The second page has a simple but powerful example of the process in action and the benefits.
Neuro-linguistics offers some excellent techniques for fine tuning the qualities of your mental images. Qualities or visual distinctions you can use to support new behaviours, change beliefs about your own capabilities, and strengthen your confidence and other resources.
The same qualities or distinctions can also be used to render those unhealthy foods we find way too tempting into something less attractive. Think of dressing up your favorite food, perhaps chocolate, so that it becomes as compelling as liver. Hummm … perhaps not. What about seeing it as something you can enjoy, just in small quantities. Better!