The stability ball, theraball, exercise ball AKA many names, is a great way to add in a challenge. Basically, it's just a cushion of air. It's not something to be afraid of, but you definitely want to master your exercise on the floor before you add it in, and maybe even have someone with you if you can to help stabilize it. We're just going to practice with a ball. You can pick it up, get used to it, and just do movements with it, that you can mimic in everyday life. Up, down. We're going to sit, bounce, just basically get warm blood flowing through the muscle. Reach, reach. Up, tap. Reach. These are just basic warm-up movements you can do with it. Turn in, and tap, then in, and tap. Sit, sit. Reach, reach, reach, reach again. You get used to moving around the ball, controlling the ball from moving away from you. Sit, reach, tap, tap. Of course, any way to really get your heart rate and blood flowing into the muscle is to raise your arms above the heart, so these will be good as well.