You can do it in the air. Or by sea.
You can do it if you're young. Or old. Or in 100-plus-degree rooms (Bikram yoga).
Indeed, yoga - the ancient Hindu practice for the mind, body and spirit - has evolved from breathing exercises and meditative poses to physical therapy, aerial choreography to a new way to firm your face, a way calm your child or a way limber up while pregnant.
"The thing about yoga is it's such a vast system, there's a million variations you can do," said Dayna Macy, spokeswoman for Yoga Journal, a monthly magazine. "Like any other pursuit in any other area, you can make lots of different judgments on what's good, what's not good, who knows, who doesn't know."
Macy has been a practitioner for two decades. She said the practice has grown into a fad over the last few years, thanks to its popularity among stars like Madonna and Sting.
Here are some of the more unusual yoga classes out there:
AntiGravity Yoga Wings
Like a high-flying circus act, with acrobats snaking up a rollicking trapeze, AntiGravity Yoga Wings promises the thrill of dance-defying gravity yoga in the air, albeit at a safer altitude.
Practitioners of AntiGravity Yoga Wings perform traditional yoga poses - or asanas - while suspended in a hanging fabric hammock.
"The class is a fusion of everything," said Robin Retherford, a former dancer and fitness buff.
Retherford teaches a weekly class at Crunch Fitness in Miami Beach, Fla.
"It combines yoga postures, dance and Pilates movements that help align the body and really strengthen the body from the core out," she said.
It is also something else: not for the faint of heart.
For first-timers, moves like the monkey wrap (hanging upside down with legs wrapped around the hammock, palms free or touching the ground) can prove daunting.
"You have to be muscular for that; you have to be a little bit trained," said Pascale Cowell, 45, a dancer from France, who has taken a handful of classes.
With the finesse of a ballerina and flexibility of a gymnast, Cowell executes a perfect midair arabesque and jumping pliés - all while straddling or holding the hammock.
The moves, she said, keep her muscles strong.
"Yes, you are sore after," she admitted, laughing.
There are occasional collisions, noted Dylan Giordano, an exceptionally flexible 16-year-old, who has found that out the hard way.
"It's the perfect class to get exercise and relax at the same time," Giordano said. "I'm not the scared type. You pick up on it. Even if you fall a few times, you get back up."
Bending, stretching and pregnant bellies? In Elizabeth Bonet's class, it makes sense.
Part yoga class, part group therapy session, the twice-weekly prenatal yoga classes at Lisa's School of Dance & Gymnastics in Plantation, Fla., appeal to pregnant women looking for a different yoga class.
Many have tried regular