You're not into wasting your time, but luckily, you don't need to devote hours at the gym for a strong core [1]. You just need to do the most effective ab-strengthening moves [2], and this four-minute workout has them all! You'll target your upper, middle, and lower abs, as well as your obliques.

The Workout

What you'll need: floor space, a pull-up bar, and a medicine ball

20 scissor abs [3]
20 diamond sit-ups [4]
20 knees-to-chest [5] hanging from a pull-up bar
20 double crunches with a medicine ball [6]
20 reverse crunches [7]

Perform this workout once a day for one week [8] and see how you feel! If you're not sure how to do each movement, see the descriptions ahead.

Scissor Abs

• Lie flat on your back. Extend your arms so they're against the sides of your body with your palms pressing into the floor, or bend your elbows and place your palms under the back of your head. Bend your knees and draw them into your ribs. This will make it easier to pull your navel in toward your spine and actively press your lower back flat on the ground.
• Lift both legs straight up toward the ceiling, continuing to engage your abs and pressing your lower back into the ground. Keeping your core strong, slowly lower your right leg down toward the ground until it is a few inches above. Then slowly, moving with control, scissor your legs, lifting your right leg back up as you lower your left leg down toward the ground.
• This counts as two reps.
• Continue alternating for a total of 20 reps.

Diamond Sit-Up

• Lie on your back and open your legs into a diamond shape (known as Butterfly pose in yoga), with the soles of your feet pressed together and knees out wide. Extend your arms overhead.
• Curl your torso up, and tap the floor in front of your feet.
• Slowly lower back to the starting position to finish off one rep.
• Complete 20 reps.

Double Crunch Pulse With Medicine Ball

• Grab a heavy dumbbell for this move. Begin lying on your back with your legs in the air, toes toward the ceiling, holding the medicine ball over your chest with straight arms. Engage your abs to press your low back into the mat while lifting your head, neck, and upper back off the mat.
• Exhale and round your low back so the bottom of the pelvis raises as you lift your upper body an inch higher off the mat. Aim the medicine ball toward your ankles as you perform this double crunch.
• Inhale, and lower your pelvis and upper back an inch toward the floor and continue slow pulsing for 20 reps.

Reverse Crunch

• Lying on your back, lift your legs in the air with your knees bent. Place your hands on the floor beside you.
• Without momentum, use your lower abs to slowly curl your hips off the floor and into your chest. Slowly lower them back to the starting position.
• This counts as one rep.
• Complete 20 reps.