Kacey DeGuardia only 15 years old when her mother died. The teenager sunk into a deep depression and became suicidal. "I was in a pretty dark place," says DeGuardia, now a 24-year-old in Philadelphia. "I was on several medications and had gone to multiple doctors to try to find the right 'cocktail' of pharmaceuticals that would fix me."

None seemed to help. But then a friend invited her to a yoga class, which she decided to try in part because she remembered her mom practicing yoga. "I had no idea what I was getting into," she says. But within a year of consistent yoga practice, she felt happy and disciplined enough to go off of her medication entirely. "The physical strength yoga offered ran parallel with my mental strength," she says.