It occurs to me that this isn't too difficult when I have good food in the house and the time/desire to prepare it.  When it will be hard is being faced with fast food or grazing on whatever crap is easy to eat.  The smart thing to do on days like that would be to have soup for dinner, or a tuna sandwich, but I think it will be too frustrating — food is such a reward, I won't be happy with a crappy dinner.  Perhaps I'd better make something yummy that I can keep in the freezer for just such an event.  I can see it is very important to make your lifestyle support the diet. 