Our second cat would fetch until he was totally exhausted.
It was all my fault. When he was a tiny kitten, he used to climb up, paw over paw, onto the bed to wake us up in the morning. He’d drop a cat toy on one of our faces and mewl pitifully. I took the toy one morning and threw it across the room. He dived off the bed and brought it back and dropped it on my face again, and he was trained to fetch (and I was trained to throw for him) just that fast.
We loved that cat beyond all reason. Mad man Muffin. He was a precious one, sharp as a tack.
George likes the sparkle balls for playing fetch. He looses them under the love seat regularly, when he has lost them all he will pat me and then walk to the love seat. He will keep doing that until I get up and move the love seat, he then will carry them out one by one and drop them at my feet then meow until I throw one for him.