4miles at 30mph , lol my dogs fit and keeps weight on without the ridiculous miles an miles of bike work or whatever. And is happy doing so...I think there has to be a balance surely? I walk mine 3-4 times a week, the rest is sprint work..let her free run/trot or whatever for piss an shit n to warm up then roughly 2sprints of 50 yards, walk about , then another 2 abit further, walk about an gradually get further out..abit of retrieving with a ball for a gradual warm down, a walk about to get her breath back, nice rub down on the muscles back home for some grub, then a walk later on at night us