Don’t waste the walk from checkout to car: Improve your posture and strengthen your upper back before even popping the trunk.

Stand with a heavy bag in one or both hands (a single weight is actually harder on your core). You must keep your arm and fingers as straight as possible while you grip the bag between your thumb and fingers (though you will bend just a little at the knuckles). 2. Walk to your destination without letting go of this challenging grip. Make sure you stand as tall as possible and keep your shoulders back.

CARRIE COCKBURN/The Globe and Mail

Originally published at The Globe & Mail .