Paul Rider runs on Mulholland Drive in Los Angeles, March 25, 2011. Researchers say a moderate running regimen is actually beneficial for the joints of people with healthy knees. Dennis J. Provost for NPR hide caption

itoggle caption Dennis J. Provost for NPR

Todd Woods and his sous chefs prepare baby greens for a quick saute at Restaurant Nora in Washington, D.C. Maggie Starbard/NPR hide caption

itoggle caption Maggie Starbard/NPR

Five-year-old Andy Villatoro plays with a toy he received with a Happy Meal at a San Francisco McDonald's last year. David Paul Morris/Getty Images hide caption

itoggle caption David Paul Morris/Getty Images