Rose LOVES fetch! I was trying to remember what I did, and I think it just came down to reaching for it and not making much effort (lol) and saying "I can't reach it" and then praising profusely when she either brought it or tossed it to me (though I'm not sure that was even needed in Rose's case, the ball getting tossed again immediately was probably enough of a reward, haha). If I put my hand out for it and say "I can't reach it" she'll put it in my hand like "THERE! NOW THROW IT ALREADY!!"