What can you say about a 70-year-old guy who can kick your butt in spin class? Outdoors, it’s below freezing, and, though technically morning, still dark as night. But there he is, bouncing along on his stationary bike like a jack rabbit and grinning happily at his heart-rate monitor, while I, nearly 30 years younger, manage to keep up only by visualizing coffee. “Just 20 minutes till coffee, just 12 minutes till coffee…”