i know ur a vollyball player but im in softball and i was pretty slow to. wat i did was i timed myself running to first base. every time i tried harder and harder to beat my time. so u could do this in ur backyard or something. the most important thing u need to do this is u need to strive to become better. hope this helped :)
Start running a mile a day. This will help your endurance greatly, even for sprints. You also need to train your muscles to be able to move quickly. Two of the best ways I have found to do this are either run the 100 Meter a lot or run up and down a lot of stairs (be careful!) and move your feet as quickly as you possibly can. You also want to try and get a good long stride while you run so that you're using up less energy than the other girls. A good thing you can do on top of that is to eat right. Avoid soda and other sugary drinks and foods and that will greatly improve your energy level.