Working up a sweat may be the easiest, most effective way to stay calm without pills, finds a new study. Arizona State University researchers analyzed a host of strategies, including meditation, yoga, stretching, and talk therapy; only prescription meds reduced anxiety better than moderate to vigorous exercise. The scientists found that burning about 850 calories a week—a 30-minute brisk walk or a 15-minute jog daily, on average—is an optimal anxiety-easing goal for many.