Prepare to eat healthy. Psych yourself up by telling yourself that you will make healthy choices. If you are going to a new restaurant, call before going and ask about healthy choices they may have. If they are not sure of the nutritional contents, ask how they prepare their food. Go ahead and know what you plan to order before you go.
Many people skip meals on a day they plan to go out to eat to allow for the extra calories.
This plan often backfires as some people become overly hungry and overeat. You may even eat a healthy snack before going out to eat to prevent over-eating at the meal. At the restaurant look carefully at the menu. Use your smarts, though. Sometimes something marked as a healthy choice may be less healthy than a menu item not marked as such.