Before any physical activity, it is best do a good warm up routine in order to prepare you body for the movements and demands that will be required in the sport/activity. This process will improve your range of motion, enhance your body coordination, improve your performance and ultimately prevent injuries.
A good warm up is specific to the sport/activity that you are about to participate in. It is always good to start moving slowly and than increase the speed and intensity gradually. For instance, if you plan on running, your warm up should include a brisk walk and than you will progress into a light jog. Your warm up should also include some dynamic stretching to stimulate your joints and muscles and improve communication with the nervous system. Lastly, make sure that your warm up includes some drills that will breakdown the motions/body movements that are involved in your sport. If we use basketball as our example, you would want to practice doing a lay up, passing the ball, shooting the ball and dribbling in a controlled fashion.