Warmup: Butt Kick With Arm Cross Stand with your legs shoulder-width apart or slightly wider. Extend your arms out in front of you and cross them at the elbow. Bring one heel up to your butt while swinging your arms open to the sides. Set your foot back down and cross your arms again, then repeat on the other side. This counts as one rep. Repeat for 30 seconds. Image Source: Gold's Gym