Sure, Madonna is a convert and Sting swears by it, but what is it exactly that they're doing? For yoga virgins, thoughts of this 4,000-year-old mind/body fitness regimen usually conjures up scary images of contorted people with their legs behind their heads or of overly new-agey folks in the lotus position chanting "OM" in incense-filled rooms. While both of these scenarios can be part of the practice of yoga, they are not what this highly dynamic, challenging and fulfilling fitness practice is limited to.