Shape, tighten and lift your butt in just eight moves with this focused resistance workout from fitness model Janine Horsley.Warm-up (not pictured)This dynamic warm-up will prepare your body for key moves. Consider it an investment.2–3 minutes: (20 seconds each)Begin with high knees, running in one place for 20 seconds. Followed with butt kickers, with heels kicking back to touch your butt, for 20 seconds.