The Hardest Workout You Can Do with Just One Dumbbell

You know that aggravating moment when you can't find the other half of your dumbbell pair because other messy gym-goers don't clean up after their sets? (UGH.)

Now, you won't have to wait around for it to turn up: You can get a kickass workout with just one dumbbell and this circuit workout from fitness expert Jen Widerstrom (the genius lady behind our 40-Day Crush Your Goals Challenge). This workout builds up your number of reps and combines straight strength with total-body power moves to not only build muscle but also get your heart pumping too. (That's one of the many perks of circuit training.)

Think you're up for the challenge? Grab a dumbbell and get cranking. (Next, put your abs to the test with the hardest obliques workout ever.)

How it works: Work through the circuit of exercises, doing 3 reps each during the first set, 6 reps each during the second set, and 9 reps each during the third set.

You'll need: A medium-weight dumbbell and a heavy-weight dumbbell

Dumbbell Crunch

A. Lie faceup with knees pointing toward ceiling and feet flat on the floor. Hold a heavy dumbbell horizontally across chest with arms wrapped around it, fingers toward face.

B. Exhale and use abdominal muscles to lift head and shoulder blades off the ground. It may only be a few inches; make sure the abs are doing the work.

C. Inhale and slowly lower head and shoulders to return to starting position.

Do 3, 6, or 9 reps.

Single-Leg Hip Thrust

A. Lie faceup with knees pointing toward ceiling and heels pressing into the floor with toes lifted. Balance a medium-weight dumbbell on one end over right hip, press left arm into the floor, and extend left leg toward the front corner of the room to start.

B. Exhale and press into the right heel to lift hips off the floor, engaging glutes to extend hips at the top, keeping left leg lifted.

C. Inhale and slowly lower hips to return to starting position.

Do 3, 6, or 9 reps. Repeat on the other side.

Dual Overhead Press

A. Stand with feet hip-width apart and one heavy dumbbell racked horizontally in front of chest, one end in each hand with elbows pointing down and tight to ribs.

B. Exhale to press dumbbell overhead, hands directly over shoulders. Keep core engaged and don't allow ribs to flare.

C. Inhale and lower with control to return to starting position.

Do 3, 6, or 9 reps.

Reverse Overhead Lunge

A. Stand with feet hip-width apart and a dumbbell in right hand. Safely rack the dumbbell up to the right shoulder and press overhead, wrist facing forward with hand stacked directly over shoulder to start.

B. Keeping core engaged, inhale to take a step backward with the right foot, lowering until both knees form 90-degree angles.

C. Exhale to press into front foot and return to starting position, keeping core engaged throughout the entire movement.

Do 3, 6, or 9 reps. Repeat on the other side.

Controlled Russian Twists

A. Sit on the floor with torso reclined at about 45 degrees, legs outstretched with knees slightly bent, and heels resting on the floor. Hold a heavy dumbbell vertically in front of chest with both hands to start.

B. Keeping core engaged, slowly rotate torso to the right, lowering the dumbbell a few inches toward the floor.

C. Return to center, then repeat, rotating to the other side. That's 1 rep.

Do 3, 6, or 9 reps.

Single-Arm Squat Clean

A. Stand with feet wider than shoulder-width apart, holding a dumbbell in the right hand between legs, palm facing the left.

B. Bend the knees slightly, then explosively extend hips and knees to clean the dumbbell up to racked position over the right shoulder, immediately lowering into a squat.

C. Press through the mid-foot to stand. Pause for a second, then drop the weight back down between legs to immediately begin the next rep.

Do 3, 6, or 9 reps. Repeat on the other side.