Push-ups are awesome because they engage every muscle from your shoulders to your toes. They're not awesome because, they're really tough to do correctly.

Celeb trainer and Reebok CrossFit Lab Owner Yumi Lee Mathews says she often sees people performing push-ups incorrectly, whether it's placing their hands too close together or too far apart ("perfect placement is key to allow your body to extend your chest, pull your lats down and keep your core tight, she says) or sagging through the lower hips and back. But, master the technique, and you'll never need your fancy gym equipment again.

Start in a plank position. "Make sure your hands are placed slightly wider and even with your chest," Mathews says. "Too high and you end up overworking your shoulders. Too narrow and you end up rolling your shoulders forward while never using your chest or arm muscles."

Your body should be in a straight line from your toes to your head, and your abs and glutes should be engaged. Lower yourself to the ground so that your chest and thighs touch, keeping your elbows close to your sides (don't let them flare out). Then, push yourself back up into the starting position.

If this is too difficult, or you start to "snake" (translation: you lift your chest up before your hips), go on your knees instead of your toes, or place your hands on an elevated surface like a desk or a bench. These are modified versions of a push up that still give you full range of motion (a phrase you'll hear a lot in CrossFit).
"Practicing full ROM [range of motion] is so important because if you continue to perform exercises in a limited ROM, then your body will only be strong and effective in that limited range," Mathews says. "You will get stronger, more efficient and will get better results in your workouts."

"I love burpees," said no one in the history of the planet ever. But, like the pushup, it works your entire body -- and adds some serious cardio benefits, which translates to toned muscles and torched fat.

Starting from a standing position, drop into a squat and put your hands on the ground, kicking your legs out behind you at the same time (so that you're in a push-up position). Drop your chest and thighs to the ground, then push your chest up as you jump your feet back into a squat position. (For speed and conditioning, burpees in Crossfit are less about performing a full push-up at the bottom.) Jump into the air and clap your hands over your head. Ta-dah! That's one rep.

To get your heart pumping, try "Roxanne:" a three-minute warm up that's set to the tune of, you guessed it, "Roxanne" by The Police. Every time you hear them sing "Roxanne," do a burpee. In the interim, do jumping jacks.

For buns that defy gravity, the lunge is the move to do. Lunges target the glutes and quads, and there are a variety of ways you can perform them.

To do a basic forward lunge, start in a standing position. Take a big step forward with one leg, so that your knee is right above your ankle. "Make sure your front heel is always down while you lunge. The focus should be on your front leg/glute/heel and never the leg that's behind," Mathews says. "I often tell people that it is similar to the lunge of 'tying your shoelaces.'" Lower your body down so that the opposite knee lightly kisses the ground. Step back into your starting position, and then repeat on the opposite leg.

You can also perform a jumping lunge; instead of stepping back into the starting position, jump up switch your legs in midair (you should land with the opposite foot forward in the lunge position).

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.