I agree with this I would just add that exercise plays another important role. Muscle burns calories. When you strength train, not only do you lose calories from the activity but you continue to lose calories from fueling the muscles you've built. Cardio is great for overall health but for weight loss muscle is the way to go. As for the failures to me there are no failures, just experiments with unexpected results. When I chow down on a candy bar at work rather then beat myself up I look at what I've eaten for the day. Usually there's an obvious reason, it's been too long between meals, didn't bring a healthy snack, or didn't get enough protein and fiber early in the day. There's lots of reasons people cheat on their health goals, usually planning ahead can help you not repeat that in the future.