We have a rescue JR (young adult) that needs exercise. Our yard is fenced with split rail, so we have to keep her on a leash as she takes off at a dead run and is so focused on squirrels that she doesn't hear us call. I walk her daily because I know she needs the exercise. I would love to play fetch with her in the house, as we have a long expanse where she can run. My problem is that she won't give the ball back to be thrown again. She cries and begs me to throw it, but I can't get it away from her. Ideas? Thanks!