ur in the same year that my DD started playing volleyball, so they did lots of running and conditioning..on her own, she began lifting dumbells to strengthen her wrists and shoulders...we started with 5, then 8lbs, now she's doing 10's like they are no big deal. She's got great lookign arms now! plus she likes to run from time to time, working on her form, sprinting and such
if u dont play another sport, anythng cardio should be good, like running and some light weightlifting