Daily 10 Miles Bad for My Dog?

[sandragonfly]

hi sorry this is boring ...but help!

first of all, nothing is wrong with my crayola....as of right now --

but as a great, great worrier, I'm afraid I'm doing too much for him? he loves to run and chase the balls constantly, won't stop until I stop (when it gets dark or rain or to other plans).

beginning of our daily adventure would be bicycling the first five miles, stop for potty (exactly same grasses), and water break then I hop back on the bike for another four miles to a park about a mile away from my home, fetches, of course!! I throw at least 50x and bike back home...

how much should he do before he breaks himself somewhere?? I now just don't feel right and didn't complain because I thought I was too busy to do this daily just for him but I've been! (except the last two weeks...).

any information? sites/facts about this? thanks!