Every morning, Jeffrey Sweeney spends two hours putting his legs behind his head. And standing on his hands, and bending backward to grab his ankles. If he doesn't always succeed -- well, that's part of the process. "The focus in yoga is on intentions," says Sweeney, 53, who has led U.S. Capital, a financial services firm in San Francisco, since he bought it in 1998. "You realize you can't necessarily achieve perfection."

Years practicing yoga: About 20

Number of asanas, or poses, he can perform: More than 140

A long journey: Sweeney had been practicing yoga for three years before he could put one leg behind his head. Adding the other leg took two more years.

Yoga in the U.S.: About 6.9 percent of American adults practice yoga at least occasionally, according to a 2008 survey by Harris Interactive and Yoga Journal.

The name game: Each asana has a name. Here, Sweeney is in Durvasasana, named after the sage Durvasa.

His second home: Sweeney spends up to two months a year in Vrindavan, India, where he practices yoga and sponsors education for local students.

Best of the best: There are six "series," or levels, of Ashtanga yoga, the type Sweeney practices. Few people ever get beyond the first or second; Sweeney has reached the fourth.

Doing his own thing: "I don't practice in the studio much anymore," he says. "When I do, it's like I'm a rock star, because a lot of people haven't seen third- or fourth-series practice."