Many sedentary individuals (and, indeed, many exercisers!) share the myth that you have to exercise at a fairly intense level to achieve cardiac benefits. To some degree, this myth grew from the advice of well-intentioned exercise physiologists, who said that improving your aerobic fitness requires at least three or four 20- to 30-minute sessions of continuous vigorous exercise every week. Without question, this advice is excellent if your only goal is improving your aerobic capacity. However, if your goal is lowering your risk of heart disease, totally different rules apply . . . you simply need to become more active. "More active" means trying to accumulate 30 minutes of moderate physical activity on most, if not all, days. Don't let the myth that you have to sweat like crazy for 30 minutes straight keep you and your heart declining . . . uh, reclining on the couch.