Squats are a foundational movement in Crossfit. And, if you want a butt that looks like it could squat for days, you've got to, well, squat for days. Squats are a great lower body workout, because they work the muscles in your glutes, hamstrings, quads and inner thighs.

An air squat is a fundamental bodyweight movement that sounds easy, but can be difficult to perform with full range of motion. "Your feet should be slightly wider than your hips and pointing more forwards than outwards," Mathews says. "This will allow you to drive your hips outward as you squat to create tension in the hips and use the glute muscles more." An ideal squat is "ass to grass:" your hip crease should fall below your knees. If you can't get that low, focus on form over depth. Meaning: keep your chest up the whole time, and never let your knees go past your toes.