5. Plank With Side Step
Works: abs, arms, back, hips
A. Lie face down with your forearms on the floor and elbows aligned under shoulders. Your hips should be off the floor; your knees and toes should be touching the floor. Tighten abs and raise knees off the floor, straightening your legs.
B. Slowly move your right foot about 12 inches to your right, keeping toes to the floor. Bring your right foot back to the starting position, and repeat sequence with your left foot.
C. Repeat 12 times each side. Avoid rounding or arching your back as your feet move side to side.
Make it easier: Skip the side steps and/or balance yourself on your knees instead of your toes.