The first exercise you ever did may be the best you'll ever do: The classic pushup trains your chest, shoulders, triceps, abdominals, lower back, and glutes. Why does it burn fat? The more muscles you work, the more muscle you build. And muscles burn calories.
How to do it: Assume the classic pushup position: legs straight, hands beneath your shoulders. Now brace your core. Keeping your body rigid, lower yourself until your chest touches the floor. Then push back up until your arms are extended.
Bodyweight Squats
Leg exercises work hundreds of muscle fibers at once, and the muscles they target are huge—calorie-chompers like your quadriceps, hamstrings, and glutes. And the squat may be a more effective muscle-builder and fat-burner than all other exercises—leg exercises as well as upper-body stuff—combined. Try this "prisoner" squat.
How to do it: Stand with your hands behind your head, your chest out, and your elbows back. Sit back at your hips and bend your knees to lower your body as far as possible without losing the natural arch of your spine. Squeeze your glutes and push yourself back to the starting position.
Pull-ups
What pushups are to pressing, pull-ups are to pulling: The granddaddy of all exercises. They work the biggest muscle group in your body—your latissimus dorsi—and train your back and biceps while testing strength and building endurance. Do as many as you can, and do more by going negative: Start at the top, then resist as you go down slowly.
How to do it: Start from a full hang, hands shoulder-width apart, palms facing away from you. Pull your chin up over the bar and then lower your body back down.
Step-Ups
Gym-goers spend hours on stair-climbers, but you can get a better workout, faster, with step-ups. Go up and down quickly and drive your knees up to get the maximum burn.
How to do it: Place one foot on a step and push down through your heel to lift your other leg up. Return to the starting position and finish all reps with one leg before switching legs and repeating the exercise.
Plank
It usually takes the stress of a job interview to get someone sweating this much without moving. But stabilizing your entire body—while simultaneously building a rock-solid core—in the plank position for 30 seconds will leave most anyone quaking.
How to do it: Assume a modified pushups position, with your elbows under your shoulders. Keep your shoulder blades back and down and your abs tight. Hold for 30 seconds, pause, and repeat.
Single-leg exercises mimic real-life movement patterns and muscle challenges—meaning they're safe and "functional" exercises—all while testing your balance and mind—meaning you'll be working harder. This move is great for those strapped to a chair all day: It strengthens the hamstrings while building flexibility.
How to do it: Stand with your feet slightly more than shoulder-width apart. Raise one foot and extend it behind you, just off the floor. Contract your glutes, brace your abs, and keep your spine naturally arched. Focusing on balance, lower yourself until your torso is parallel to the floor. Initiate the movement by pushing your hips back. Push back up to the starting position.
Stick-Up
Don't be fooled by this simple exercise: Performed correctly—with your shoulders, elbows, and wrists in constant contact with the wall—it's a tough back exercise that challenges your central nervous system for additional calorie burn.
How to do it: Stand with your back against a wall, feet 6 inches away from the wall. Stick your hands up overhead. Keeping your shoulders, elbows, and wrists in contact with the wall, slide your arms down the wall and tuck your elbows into your sides. Return to the starting position.
T Pushup
There are hundreds of ways to tweak the classic pushup to make the all-time great exercise all new. This version includes rotation and core stabilization—both targeting and sculpting the abs.
How to do it: With hands shoulder-width apart on the floor, do a pushup. When your arms are straight, lift your right hand and rotate so that you raise your right arm straight up over your shoulder and your body forms a T. Bring your hand back to the floor. Do another pushup, working the left side.
V-Up and Roll
Crunches work—they just don't work smart or hard enough. Variations like this one reduce the stress on your back (smarter) and use more muscles together (harder).
How to do it: Lie on your back with your legs straight. Hold your arms straight above your chest, your fingers pointing toward the wall behind you. Contracting your abdominal muscles, fold your body up by lifting your legs off the floor and stretching your arms toward your toes. Keep your back straight. Pause, then return to the starting position.
Shoulder Press Pushup
Lots of classic bodybuilding moves boil down to one thing: Lifting heavy stuff over your head. But you don't need weights to get the same benefit. By using a bench (or chair), this pushup variation flips that over-the-head movement upside-down for a new twist that provides the same old results.
How to do it: Place your feet on a bench and hands on the floor slightly wider than shoulder-width. Pike your hips up in the air, so you are as vertical as you can be. Slowly lower your head to the floor. Pause, and push with your shoulders and triceps back to the start position.