Get ship-shape for summer with Sara Fennell's butt workout.

Donkey Kicks for a firm butt - Women's Health & Fitness

Starting on your hands and knees, keeping your core tight and back flat, raise 1 leg and keeping knee at 90 degrees. Push that leg as high as you can in the air and lower back down, repeat for 12 reps, then switch legs.

Aim for 4 sets of 12 reps.

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Photo credit: Jamie Watling Photography