The more active you are, the better, Meng says.

Exercise boosts your heart health, builds muscle and bone strength, and wards off health problems.

Aim for 2 and a half hours of moderate activity, like brisk walking or dancing, every week. If you're OK with vigorous exercise, stick to 1 hour and 15 minutes a week of things like running or playing tennis. Add a couple of days of strength training, too.

If you're busy, try short bursts of activity throughout the day. Walk often.

A good target is 10,000 steps a day. Take the stairs. Park your car far away from your destination.