My 8 month old springer enjoys chasing balls, toys etc but doesn't bring them back. The only way to play is to have two toys and throw the second one so I can get the first. It's not as bad as it sounds - I don't have to go running over the field for the ball or anything, he does come near me to drop it, then will sit when asked to before I throw it again, but I have to show him the second toy to get him to drop. I want him to bring a ball back to my feet! How do I teach this?