I'll second what dougclyde and Myosmith said. You've taken the first step which is the hardest. I've found that if I have 'bad' food in the house I'll be sucked into it. I've killed so many chickens, apples and other 'better' foods in the past 8 months it's not even funny.
You might want to look for the WIN (Weekly Inspirational Network thread); this weeks -
http://www.bikeforums.net/showthread...rch-5-March-11
Good luck