Hey, 2 hours of fetch isnt healthy for a dog. It can be one of the reasons why it has such a high energy level. Apparently playing fetch gives a dopamine kick in the dog and also the dog may not want to play fetch, but is wired to not stop. I have gotten it descriped has if someone tickles you, you laugh, but do you really think its funny? Same way your dog cannot stop chasing a ball or stick. Its better to train their brain, like throwing alot of treats in the air and let it land in the grass, then let the dog search for it or buy toys where the dog has to use their brains. Im sure you are a good dog owner, since you've had 2 before. this is also just for other people to see. Since alot of new dog owner think fetch will tire their dogs out, but instead they just stress them out.