My dogs run. They walk. They hike. They swim. Nothing bad at all with exercise for animals, actually animals are going the way of humans and becoming overweight, so exercise is very good for them.
My brother had a chocolate lab/pitbull mix and he's a triathlete. He took her for 20 mile runs, 2 mile swims (with a lifejacket) all her life. She's 13.5 years old now and in EXCELLENT health. She has arthritis in her legs now, but she's super old for her breed! The vets are always impressed when they see her and my brother has to tell them her age, they usually say they never would have guessed by looking at her. She still hikes and walks, even though her legs hurt. She won't be left behind!
This morning was cool but VERY humid. This humidity is stupid by the way and making it hard to live, breathe, anything, I hate it!
Anyways..... we went out for a 2 mile walk with the boys. When we were close to getting home (the house next to our house) is when my boys were done. They were starting to stop a lot, trying to sit down in the road, walking through the puddles. All the signs of being done. Thankfully we were just about home at that point. They can usually go 4 miles w/o a problem, but the humidity was killing us all I think! Plus they spend the first 1.5 miles trying to run/walk on their leashes, pulling me so that tires them out faster I think. They are just soooo exuberant on their walks, they love them more than any dog I've ever seen. LOL