Pre-philosophical speculations and diverse ascetic practices of first millennium BCE were systematized into a formal philosophy in early centuries CE by the 'Yoga Sutras of Patanjali'. Hindu monks, beginning with Swami Vivekananda, brought yoga to the West in the late 19th century. In the 1980s, yoga became popular as a physical system of health exercises across the Western world. Many studies have tried to determine the effectiveness of yoga as a complementary intervention for cancer, schizophrenia, asthma and heart patients. In a national survey, long-term yoga practitioners in the United States reported musculo–skeletal and mental health improvements. Yoga is utilized therapeutically to help improve posture, strength, functional capacity and mobility. It is the gold standard exercise to help improve structural alignment.