1. Your legs need you to walk. Sitting doesn't give a damn.
Twenty years running physicals for fleet drivers, I watched healthy men age in fast-forward. The cab doesn't care how strong you are. Sit long enough and your calves — the pump that pushes blood back to the heart — simply stop working. Blood pools in the lower legs.
A protein called fibrin starts coating vessel walls. Every hour still, it builds a little more. You can't feel it. Won't see it on a blood test. By the time legs go numb stepping out of the cab, it's been building for years.
The drivers who didn't make it weren't weak. They just didn't know. And nobody told them.


