In our Western culture, many people use Yoga asana as a stretching tool to keep the body limber and agile. To this extent there is no better practice. Traditionally, however, Yoga postures are a part of a much greater spiritual journey.
Yoga is a complete science of helping the mind to become clear or pure.
A clear mind is not affected by stress and a clear mind produces a healthy body. While the health benefits of a mind at peace are irrefutable, what is even more exciting is that a person with a clear mind is also aware of their deeper spiritual nature or connection. We say in Ayurveda that all disease is the end result of forgetting our spiritual nature. Hence, Ayurveda and Yoga strive to help a person re-connect to their true nature through direct experience. In fact, Ayurveda is the healing side of Yoga, and Yoga is the spiritual side of Ayurveda.