Originally Posted by
Catsmine
I'm afraid I have to disagree with either your numbers or your definition of "hard exercise." If you mean prolonged exercise I'm with you, as puppies run out of steam quickly but build it back up just as fast. A 15-30 minute walk is easy for a lab, even at only 4 months. He'll pass out immediately on coming home for maybe even two whole hours.
"Hard" exercise is somewhat different, depending on the exercise. Field dogs begin training at about 4 months, and that includes running, swimming, and leaping for a couple of hours at a time. Without extensive experience, though, home trainer/owners should stick with basic obedience and fetch games, just to avoid overtaxing a growing pup.