What are some good warm-up and cool-down exercises?

Be creative. Follow some general principles & you can be creative to find something that works for you. A good warm-up involves big movements (to increase your heart rate), using the muscle you are about to exercise. The cool-down signals your body that it is time to relax and allows your systems (including your heart rate) to slowly throttle down. Check this link for an example. http://youtu.be/7j2riuhkkxo.