Stay focused on why you need to eat right and exercise like DIDS70 said.
PLAN - I can't stress this enough. If you fail to plan you plan to fail. For instance if you have a dinner out coming up, look up the restaurants menu and nutrion info online before you go and PLAN what you will eat. You'll find that when you take the time to plan your meals and work outs and prepare by having the ingredients you need on hand etc. that is is SO much easier to stay on track. Soon the things that tempt you now won't even sound good and exercising will give you more energy.