ARMSTRONG is a professional cyclist in part because he is a freak of nature; his heart is said to be a third larger than a normal man's heart. Armstrong is a champion cyclist, however, because he trained as hard as or harder than any rider in the peloton. During his seven Tour victories, he was a master of tactics who evaded crashes on the flats and dominated the time trials. Often, he was the best climber as well—not easy for a cyclist with a five-eleven frame that comfortably supports 180 pounds. At the Tour's legendary "beyond category" climbs, such as Mont Ventoux and l'Alpe d'Huez, a half-pound can make a significant difference, and many of Armstrong's rivals on the steeps were 135-pound featherweights. Armstrong compensated by developing the most efficient engine—credit his work with coach Chris Carmichael and a power ergometer—and watching his weight like a college wrestler.

So I was a little surprised when I showed up at his house after the photo shoot to find him stuffing sushi in his mouth by the handful. "I only had a smoothie after my ride this morning," he explained, anticipating my question.

We were standing in his kitchen before the interview, gathered around a giant granite-topped island. With us were Armstrong's new girlfriend, Anna Hansen, and Mark Higgins, his longtime manager. Hansen offered me a Whole Foods chocolate-chip cookie. When Armstrong saw the package, his eyes went big.

"Have you had one of those before?" he asked. "Oh, they're the best. Oh, man, I hate those things. I'll eat a whole box by myself."

There were 12 cookies in the package.

How much do you weigh now?
A hundred sixty-eight to 170 pounds.

And what was your peak after 2005?
The most? One-eighty-three when I started this whole thing. But I would start most seasons at 180. At the Tour I would be 163. It's good that I got a little ahead of it; I'm ten pounds lighter than I would normally start. That's hard on the body, trying to diet.

Very few people think a 38-year-old could win the Tour de France.
Thirty-seven. I'll be 37 and eleven-twelfths. [Laughs] No, 37 and five-sixths.

Very few people think a 37-and-five-sixths-year-old can win the Tour.
I'm not far from those people. But I think it's healthy to have my doubts and healthy to be aware of my body and aware of my fitness. For a lot of reasons, [my age] motivates me. And I don't want to be the guy that says, "This is definitely going to work" and then it doesn't work and you're crushed.

Did you get some inspiration from watching Dara Torres?
Yes and no. It's a different type of event. You can't compare a 50 free with a Tour de France. But the lady who won the Olympic marathon [Constantina Tomescu] was 38. Science will tell you that endurance athletes in their upper thirties are no weaker or slower than the young ones. The problem for a 37-year-old athlete is they've probably been doing it for 25 years. At that point the mind goes, "Let's do something else here. This is enough."

You feel you benefited from time off.
My mind feels like it's 1998, '99. And you could argue that I've come back from harder things. That's the way I look at it. I'm coming back three years off, four years off, not training a lot, out of competition. But in 1997, '98, I came back from a year and a half off, fighting cancer, high-dose chemotherapy, radiation, surgery—just no time on the bike. So I've tried to take an optimistic viewpoint on it.