It's not uncommon to feel like as you age, you gain a gut and lose your butt. As the years wear on, muscle tone - especially in the butt, which is the largest muscle group of the body - diminishes if you don't work to stop it. "Many of us sit down all day and actually deactivate our glutes," says personal trainer Lisa Reed. When glutes become weak, the muscle loss also leads to a slowing of metabolism - the rate at which your body burns kilojoules - thus contributing to fat gain (i.e., the gut).

Luckily, there's a two-for-one solution: strength training. When you target the glutes, quads, and hamstrings, you can build muscle and boost overall metabolic power while restoring tone to your butt.

These exercises, recommended by Reed, involve big movement patterns for the most muscle-building and metabolism-boosting benefits. Do 8 to 12 reps each, slow and controlled with good form.