When I was in fifth grade, I aced the Presidential Fitness Test. Not because I was some athletic prodigy — I was a large child who’d later become a big man — but because we had a pull-up bar at home. My parents had installed it in a doorway, and like my 5-year-old daughter today, I’d been doing dead hangs since before I could walk. When test day came, I knocked out pull-ups even as some skinnier children struggled. I held my own on the run. I bent far past my toes. None of this seemed remarkable to me. It was just what you did, growing up on the farm and playing and working outdoors.