When Trace Bonner launched Holy Cow in West Ashley's South Windermere Shopping Center last summer, she didn't know what to expect. Now she's teaching 16 classes a week and adding another instructor. And while she credits the center's success in part to its cute cow logo and convenient location, there's no question that there's a revived interest in yoga across America. The ancient Indian practice of yoga first arrived in the US at the beginning of the 20th century, but didn't really catch on until 1969 with chants at Woodstock. Now, after being overshadowed by the aerobics craze in the '80s and early '90s, yoga is once again attracting followers, with many looking for relief from ailments and injuries or from the stress of daily life. Baby boomers, worn out from years of jogging and bouncy workouts, are back on board. But interest is growing with other age groups, too, from college students to senior citizens to celebrities. The surge in interest is being fueled partly by doctors' growing acceptance of yoga's healing potential. Mainstream medicine has adopted yoga as a gentle therapeutic method for treating a number of illnesses, so more and more doctors are referring their patients to yoga. Initial trials have shown yoga can help people with arthritis, carpal tunnel syndrome, asthma and cardiac risk factors.