I would sit down at the computer and find a really great healthy new recipe to try. Then, I would plan out all my meals for the next week - breakfast/lunch/dinner/snacks. I would make a grocery list with everything I will need for the week. Then, I would go to the grocery store and buy JUST the stuff on my list. I would come home and do as much pre-work as possible. If I plan to have bagged veggies and dip for snacks for the week, I will get them bagged up and ready. If I plan to take salads/sandwichs to work for lunch, I would get them ready. If I had time, I would make my new healthy recipe (hopefully, it's something that might save well - pasta, soup) and have it ready and in the frig for when I need it.
Then, I would follow my plan. If I don't follow the plan, all that food will go to waste and I hate foods going to waste.
I would set a reward, if I followed the plan for a week, I would get something nice - like a pedicure or a pretty new pair of sandals for the summer, or a necklace from this site (love this one of a kind stuff). http://www.snazzygirl.com/2mile/
After a successful week, I would feel great and motivated.