Perfect running partner?

He runs with grace, he doesn't need a leash (except when the dog police are out), he never tires, complains or whines. My perfect running partner follows behind me or in front at the perfect distance and can run up any hill at full speed and then comes back down at full speed to come get me. He doesn't care where we go, or how long we stay out. He likes swampy mud, he likes hills. Is he the perfect running partner?