We never stop. We go to school, we go to work, the kids soccer game, cruising youtube, cleaning the house...does it ever stop???? Granted, I'm the worst at stopping but I am a big proponent of rest and recovery in diet and exercise.
For those over-achievers out there, hitting the gym twice a day, working full-time and all the other commitments you have, don't you just feel burnt out? I know I did last summer. I was bordering on over-training syndrome (http://sportsmedicine.about.com/cs/overtraining/a/aa062499a.htm). I was cooked, nothing left it, it wasn't fun, I wasn't proud of myself! I was violating one of my very own cardinal rules~~~REST AND RECOVER. When we push ourselves, in particular in the gym, we tear ourselves down. In lifting weights, we make micro tears in our muscles in the negative phase of the lift. This isn't building our muscles, this is damaging them. The way we increase and improve our muscular strength is from the recovery. The rest day after a hard lift is when these tears are healed together creating a larger and stronger muscle fiber. It's absolutely essential to have a recovery day when lifting.
I also find the "free" day or diet free period is as important as the diet itself. I hate feeling like I can't or shouldn't have something but if I know that I have a "free" day coming up, I can usually talk myself into waiting. It is similar in the concept that I posted with the zig zag diet. By not providing a level, steady state amount of calories/nutrients, the body has to work harder to metabolize and digest them. If you stay in a low carb state for long periods of time, your body will begin to work more efficiently with less carbs and you'll see your diet starting to slow. If you throw a high carb day in there, your body is suddenly working harder to process the new way eating and thus kicking you back into a more efficient calorie burning machine!
So take this as your permission slip to take a break! Enjoy a day off and find a renewed sense of optimism.