For ten years, Leo had been a weekend warrior with a death wish. He’d climb steep ice in the Canadian Rockies until his forearms screamed, then drink whiskey in a borrowed truck and drive home on fumes. He measured success in survival. His training log was a tangle of scrawled, half-literate notes on gas station receipts: “Felt strong.” “Pumped out.” “Maybe don’t eat gas station burrito before crux.”

Leo snorted. But he kept reading.

The log demanded specificity. No more “climbed something hard.” It asked for heart rate zones, vertical gain per hour, rest ratios, and something called “aerobic deficiency” – a diagnosis that hit like a piton to the chest. You think you’re fit because you can suffer. Suffering is not fitness. Fitness is the ability to recover before the next move.