I can go about an hour. Here is how it works.

Get up early, walk lamb for an hour
Go feed and work with horses for about 2 hours
Take dog on walk ONE BY ONE ( I have 6 dogs)
Rest for a while on computer
Get back up, throw ball for Ginger, run with lamb, and dogs
Get lamb on leash after run, walk her 1 hour and a half ( about)
Rest a while
Get up and go see, feed and ride horses

That keeps me good and exersized.