No weights? No problem. Tone your abs and core with one single bodyweight move — the plank. These five variations will get your heart pumping and your arms and core burning. It only takes three minutes, so if you want a longer workout, repeat this circuit two or three times.

Frogger

• Begin in plank position with straight arms and legs.
• Gently hop the feet forward behind the hands. Then hop the feet back to plank position. This counts as one rep.
• Complete as many reps as you can for 30 seconds.

Superwoman Plank

• Come into plank position.
• Bend the elbows, and lower the belly to the floor. Take a lift by actively bending the elbows behind you, squeezing the shoulder blades together and raising the legs as high as you can.
• Plant the palms on the floor underneath the shoulders, and press back up to plank. This counts as one rep.
• Repeat for 30 seconds.

Side Plank Crunch

• Lower into a side elbow plank with your left elbow down and your right hand behind your head.
• Keeping your torso stable and your waist lifted, bring your right leg up toward your shoulder to lightly tap your right elbow.
• Lengthen your right leg back to the starting position to complete one rep.
• Do as many reps as you can for 30 seconds. Then switch sides for another 30 seconds.

Plank With Creepy Crawler

• Come into plank position.
• Bring your right knee to your right elbow, and then return the right leg back to plank position.
• Repeat this action on the left side to complete one rep.
• Continue alternating for as many reps as you can for 30 seconds.

Dolphin Dive

• Come into Quarter Dog [1] with the forearms parallel. Press your hips and shoulders back toward your feet, lengthening through your spine. Walk your toes away from you a couple inches.
• With fingers spread wide, dive forward, lowering the chin so it's barely touching the floor in front of the fingertips. The shoulders should hover over the wrists, and the elbows should remain in line with the middle fingers.
• Press back to Quarter Dog to complete one rep.
• Do as many reps as you can for 30 seconds.