Why: Targets your upper abs, lower abs and obliques with one movement.
How: Lie on your back with your legs straight and arms overhead. Lift your left leg up and touch your foot with your right hand. Lower your leg and arm to the starting position. Repeat with your opposite arm and leg, and continue in alternating fashion for the specified number of reps.
Sets/Reps: 2×5 each side
Photo Credit: Getty Images // Thinkstock