Exercise 'must be tough to work'
To be healthy, you really do need to break into a sweat when you exercise, say experts.
American College of Sports Medicine members are concerned official advice to do 30 minutes of gentle exercise each day is being misconstrued.
Some may take this to include a mere stroll to the car, Circulation reports.
People should do at least 30 minutes of moderate exercise five days a week, or 20 minutes of vigorous exercise, like jogging, three days a week, they say.