This 10-Minute Abs and Butt Workout Will Leave You the Best Kind of Sore

You'll definitely feel your glutes and hamstrings kick into gear with this butt exercise — but by holding your hips steady, it's secretly working your core, too. There's no modification shown for this final move, but you can make it easier by lowering your heels to the floor.

• Lie on your back with your knees bent and feet planted on the floor, hip-width apart. Place your hands flat on the ground at your sides.
• Lift your heels off the floor so you're balanced on your toes. Engage your core then squeeze your glutes to lift your hips off the floor, forming a straight diagonal line with your body from shoulders to knees. This is your starting position.
• Without lowering your hips, slowly press your knees out to the sides. Stay balanced on your toes and keep your torso in line, ensuring that your core stays engaged and your back is flat.
• Draw your knees back in toward center to return to the starting position.
• That's one rep. Repeat for 30 seconds.