When I am being 'good', lol, I try to plan meals within certain guidelines - i.e., low carbs, dukan, veggie, etc.
I try to keep in the freezer some kind of filling but healthy stuff that I can heat and serve within minutes - currently, I am liking Costco's frozen won tons - makes a terrific soup, and the ingredients are all natural. Also, the frozen French onion soups - light but delicious and filling.
In general, I'll aim for some kind of soup for lunch and a piece of fruit. If I'm really hungry, I'll go get something at the deli, like salad with roast beef slices, stuff like that.
If I do go to the trouble of cooking, I do try to cook for several meals, so as to make it easy to just pop something in the microwave in case it's late and I'm tired, or if I want a midnight snack - adding a dash of wine or some chopped parsley to freshen it up.