Exercise B: Farmer's Walk
Grab a pair of heavy dumbbells and let them hang at arm's length by your sides. Keeping your shoulders back, walk for as long as you can.
If you can go longer than 45 seconds, use heavier weights. "In addition to core strength and stability, the farmer's walk builds mental toughness, which helps you power through plateaus," says Smith.
Stay in shape in a fitness class.