Build Lean Muscle With This 20-Minute Ab, Butt, and Leg Workout by Brittany Watts

• Start with your feet slightly further apart than hip-width and your arms raised overhead.
• Maintaining an upright position, drive your left knee up as you simultaneously bring your hands down to connect with the top of your left knee. Be sure to keep your body tall and not to collapse at the hips.
• Return your arms to the overhead position, and with control, bring your left foot back down to the ground.
• This counts as one rep.
• Complete 25 reps driving the left knee up, and then complete 25 reps driving the right knee up.

Take 30 seconds of rest, and then repeat this circuit for a total of three rounds. Don't forget to cool down once you've finished the workout!