my 4 month old pit is awesome, but he has too much energy. I play with him as much as i can but i just cant seem to tire him out. when he plays with his puppy friends he outlasts them easily. so i was wondering if anyone had any toys or things around that he could use to exert some of this energy on his own. so he could be excersising even when im not around. anything that burns a lot of energy that he can use on his own?