Joel Harper demos the squat exercise.

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(Strengthens legs)

With your arms stretched to your sides, palms up, and your feet turned out, hip-width apart, squat so your hamstrings are parallel to the ground (or close to it) while your knees remain in line with your heels. Now straighten your legs and rise back up, squeezing your butt and curling your tailbone under you. Do 25 times. To make it more difficult, hold in the down position and pulse 25 times.