Sure, we have the easiest starvation-free, hassle-free eating and exercise program ever. But your body won't stay strong and lean unless your mind tells it to. Our three-part plan puts all the pieces together. "The key reason people succeed or fail with a new program is the mental part of it," says Bobby McGee, a sports psychologist and running coach to winning Olympians and author of Magical Running (bobbymcgee.com). It's a fact that your body reacts physiologically to your thoughts. So thinking big can make major changes happen.

On its own, your body is naturally conservative when you ask it to do something. If you lift a weight, your body recruits just enough muscle to do it safely, but not necessarily heroically. So when you want to outperform yourself, "you have to fool the body into recruiting more muscle," says McGee, which you can do with your mind. If you think you can't run a seven-minute mile, for instance, your body begins to switch off muscle, leaving you weak and fatigued. But if you think positively, your body will recruit more muscle to do it. Lab experiments have shown the same thing: "If you put athletes on a treadmill and show them videos of themselves running badly in a race, their VO2 max [the amount of oxygen their bodies can process] will go down," says McGee. "But as soon as they are shown tapes of themselves performing well, their VO2 max goes up."

Dedicate time to changing your mind, and the payoff will be overwhelming.

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Alter your brain chemistry for success. Focusing on negative thoughts (imagining pain, for instance) activates the part of the brain that responds to fear. But positive thinking (imagining that the pain isn't so bad) "actually changes the brain and how it's organized," says neurologist Richard Restak, M.D., author of The Naked Brain. As a result, your body will respond differently. If you're running, for example, change your mid-workout "my legs are so tired" thought to "this means I'm getting stronger and leaner," and your performance will usually improve.

Let your mind sculpt your body. Focusing on what you're doing in the gym can dramatically increase the benefits you get from it. In fact, one study showed that people who imagined flexing their biceps but did no actual lifting increased strength by 13.4 percent over 12 weeks. "When you think about carrying out an action, you stimulate some of the same parts of the brain that you would if you were actually carrying out the exercise," says Restak. So when you do perform the exercise, your brain is that much better at recruiting muscle to do the work.

Smell and taste your victory every step of the way. Visualization is an old trick, but here's what most people do wrong: They watch themselves achieve their goals as if they're watching a movie. Instead, really feel the burn in your legs and hear the roar of the crowd, and you have a better chance of making it happen. If, for instance, you have a hard time getting to the gym, accept that you'll be dragging yourself there on some days, but also visualize what it feels like to have your energy build as you begin your workout, says Kay Porter, Ph.D., author of The Mental Athlete.

Plan for failure. While you need to visualize success, you also need to know that you won't be successful every time. And when you're not, don't just blow it off with an, "Oh well, I tried," says McGee. "'Trying' is a way of not taking responsibility," he says, because it lets you off the hook. There's nothing wrong with a night of overeating, a skipped workout, or your worst 5K time ever; it's essential for success as long as you learn something from it about how to improve your performance next time.

Appreciate discomfort. "Change doesn't happen in your comfort zone," says body coach Patricia Moreno of Equinox Fitness in New York City. "Your body won't give you anything you don't ask for." Daring to go beyond where you've been before means choosing to be greater, faster, smarter, stronger, and more powerful. That's a pretty big payoff for an extra push-up.

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