There is a man, neither old nor young, who uses the stair-stepper machine at the climbing gym. I only see him on the stair-stepper, and I always see him on the stair-stepper. He wears heavy boots and a weighted backpack. He trudges alone, in the corner of the room, for hours. He’s training to climb Mt. McKinley, the highest peak in North America. “Hopefully,” he says.