Scientists are working to understand what hormonal and physiological cues in the body lead the brain to respond to food emotionally. hide caption

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As we age, our muscles deteriorate, and they don't repair as quickly as they used to. But the good news is that exercise and weightlifting can still make muscles stronger. Al Bello/Getty Images hide caption

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Bob Karch is the chairman and a professor in the Department of Health and Fitness at American University. Here, he helps cross-country champion Steve Hallinan check his heart rate while cross-training on the bike. Allison Aubrey/NPR hide caption

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A barefooted runner takes to the streets. Charlie Riedel/AP hide caption

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Budget Office Director Peter Orszag (far right) has found a way to turn walking into a competitive sport on Capitol Hill. Here, he walks through the Eisenhower Executive Office Building with Vice President Biden, President Obama and Treasury Secretary Timothy Geithner. Charles Dharapak/AP hide caption

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