Every morning, on the way to the office, I walk by a dog park. It's in a nice part of the city, so it's a lot of fancy dogs with hypoallergenic hair and such, although I doubt the dogs know that. What I always enjoy about the dog park is how excited the dogs are. Excited to chase a ball, excited to sniff other dogs, excited to roll in the grass. You never see a dog walk after a ball, even old dogs will run their slow wobbly-kneed run after a thrown ball.
It's not just dogs, I see my daughter do it as well. If she sees a friend on the way into daycare she runs all the way to the daycare door. If we say she can watch TV, she runs to the couch, tell her she can have a cookie she runs to the table and waits for it. She could walk and arrive concurrently with the cookie, but that thought never crosses her mind.
You rarely see adults run out of sheer joy. The dog owners usually stand around, many looking more interested in the prospect of being able to leave the park than being at the park. The parents at daycare don't run along with their kids, and I assume they, like I, do not run to work if we meet a co-worker on the way there. You see someone running in something other than obvious jogging attire and you wonder what they're late for, or if they're really moving, what they're running from.
I haven't started running out of excitement. I do some days stop and watch the dogs do it.