MY FATHER'S RACE finished on March 3. Though his sickness had lasted barely six months, half the impossibly short "long-term average survival" the doctors had given us at the start, he had endured. He'd kept going.

I had spent a year thinking about endurance. Trying to understand it as a function of physiology, of lactic acid and capillary networks. Trying to understand it as the ability to fight through the drama of pain. But now I understood it, too, as a kind of elegance, a lightness that could come only from such deep comfort with yourself that you began to forget about yourself. Something no heart monitor would ever measure.

Dad died in time to let me go to Norway for the Birkebeiner. Once I'd thought that this would be the epic end of my saga, but now I knew that whatever epiphanies I'd been allotted had come at the edge of his sickbed. Now there was just the pleasure of enduring in a great crowd of others doing the same—old men, some of them 80 and 85, a little stiff in their Lycra, but still elegant. They'd been skiing these hills 50 years ago, tracking down Allied airdrops in the woods, and they did so still, for the sheer joy of it.

The course was brutal as advertised, and I was in no danger of letting loose another epic performance. But never mind. I went deep inside, kept track of my weakening calves and my tightening chest, measured my resources against the distance left to go. And it all came out just fine—a little over four hours of hard skiing, ending with a series of sharp downhills into the Olympic stadium filled with brass bands and cheering crowds. I finished just above the middle of my age group, which I declared a great victory, considering they were all Norwegians. But I took my conquest as quietly as everyone else—there was no whooping or hollering on the bus to the showers, just satisfied and tired smiles. The year was over, and it was time for a smoked salmon pizza and a bottle of Ringnes and some Tiger Balm to rub on my aching thighs.

The next morning dawned clear and cold, and Sue and Sophie and I went for another ski. And for the first time in along time, it meant nothing at all.  

Longtime contributor Bill McKibben is the author of Hope, Human and Wild, among other books. This article is adapted from his forthcoming book Long Distance: A Year of Living Strenuously, which will be published next month by Simon & Schuster.