Peanut will do that as well...only when we take long walks. When I take him for 3-4 miles which I usually do, and he has to stop at everything to smell it will usually take us about an hour 1/2...he will start to lay down and look and look at me like "mom I am done" but I say come on and he keeps it going

then we come home and he takes about a 2 hour nap