For a documentary on yoga in America, my partner and I recently interviewed renowned cardiologist Mehmet Oz. “If you come to me with a heart condition,” he said, “and you expect me to cure you, but then after the operation you go back to your old habits or you don’t exercise or you don’t do yoga, then all that I’ve done is palliate your problem. You’ll be back with the same problem again, expecting me to fix it. The bottom line is that if your heart doesn’t have a reason to go on beating, it won’t.”