When I started college there was a beautiful, slim young women in my dorm who was on the track team. What I remember about her--I think her name was Denise--was that she didn't overeat. One of the other girls asked her one day why she didn't eat more, with all the exercise she got.
Denise replied that she was not hungry enough to eat more. She said that when she is exercising, her appetite stays in control. When she is taking a break from running, her appetite increases.
That little snippet of overheard conversation has stuck with me all these years. It seems to me that it's easy to justify eating more because I'm exercising now, but what Denise was saying was that a fit and healthy body will regulate itself, but if you let one part go, the others get out of control as well.
I'm obviously not there yet; I still have to think about how much I eat and sometimes I still overdo it, but it is definitely getting easier.
The good news is that after plateauing for a couple of weeks, I lost 0.6 pounds this week. Every little bit counts!