You've said it, done it. You're a good girl (or boy) when you stick to your diet, or exercise, or stop-smoking program. You're a bad girl (or boy) when you screw up that program.
The reward-punishment cycle is hard to stop when it's so deeply ingrained in us, but it is possible to end or at least reduce the occurence of the negative stuff. One of the things that has helped me regain control over my eating behavior (on many levels) is keeping a food log.
Entering my food intake (including time of day, amounts, the eating environment, my physical hunger, any eating problems, and how I felt emotionally before, during, and after eating) has forced me to put on my scientist hat. I've always thought of myself as an intuitive, creative person, not a scientific one, but sometimes when I act a part, I become the part. When I've written down all this data about my eating, it's easier for me to see it with an objective eye. Patterns that are invisible to me when I'm in the middle of a situation become clear when I've backed far enough away from it. Things that I didn't understand when they happened to me yesterday have new meaning when I study them today.
Things that I don't want to understand also become clearer to me when I see them in my food log. For example, after my weight loss surgery it became increasingly difficult for me to eat when sharing a meal with my elderly mother. Twenty years earlier, eating with her was a joy because we both loved food and the conversation that surrounds a meal. As she grew older, fussier, more confused, more demanding, the joy drained away and I found myself in the middle of painful stuck episodes every single time we ate together. A few hours after each incident, I would find myself seeking comfort in food, like stopping at Baskin-Robbin's for a 670-calorie Cappuccino Blast after leaving Mom in the capable hands of her assisted living facility staff.
I loved my mom, I loved our old ritual of enjoying meals together, but it was just wasn't working any more. Time to make a change. After that realization, when it was time for family meal, I spent the time fussing over Mom instead of trying to eat my own meal. I ate my meal later, when Mom was safely tucked in bed.
The take-home message here is this. Try to avoid the extremes of "good girl, bad girl" thinking, not just in your eating but in your exercise, work, parenting, and anything else you undertake. Sometimes a little bit good can be good enough, and a little bit bad doesn't signifty the collapse of western civilization. Try to be a kind, tolerant, bur firm parent to yourself. Instead of screaming, "Bad girl!" when you fall off the bandwagon, give yourself a boost back up onto the wagon by saying, "That wasn't good, but I know you can do better, so go do it!"