Yoga is different things to different people, so what it means to you will depend greatly on how you were introduced to it and how you enjoyed your initial experiences with it.
For some people Yoga is simply a method of exercising that ensures they have a healthy supple body. For other people Yoga transcends a method of exercise and is a spiritual experience that allows them to find the balance and centering their lives need. This type of Yoga comes closer to a life philosophy than any other.
Ashtanga Vinyasa yoga is often placed in this final type when assessing its place as a Yoga discipline. It descends from a document known as Korunta Yoga which deals with the 8 spiritual movements which are described by Patanjali in Sutra Yoga.
Today most Yoga disciplines are directly descended from the descriptions of Yoga exercises in these documents, and so most forms of Yoga are variations of Ashtanga Vinyasi.
Getting a complete understanding of Ashtanga Yoga is important as its proponents treat it as more that a form of exercise. While it's base is in physical movement it is suggested that its power in fact comes from the strength of spirit that is developed from regular and disciplined practice of the 8 stages of Yoga.
Through the eight stages of Yoga the body and mind become pure, and so they are seen as a purifying discipline.
Furthermore the discipline of Ashtanga Vinyasa deals with a profound and deep way of relating to others. The closest word to describe this aspect of the Yoga discipline is manners, but it really does go beyond that.
Yoga is a discipline of balance, and the physical balance required to complete many of the exercises should be mirrored by an internal balance or harmony of the soul. It is said that a hyperactive person cannot be successful with Yoga and this is true on several levels.
Firstly they lack the discipline to sit calmly through the exercises, but they also lack the mental calm to focus wholly and completely on a single task. Yoga requires deep concentrating on the simple act of breathing and feeling the breath bring life to different areas of your body.
The power of Yoga is found in its combination of the physical strength and flexibility needed to complete movements and the mental discipline that is required to maintain them. Yoga is not just a form of exercise but most often it is thought of as a form of meditation.
Meditating successfully with Yoga requires a pureness of thought and singularity of focus that is not found in most modern exercise programs. It seeks to bring the body back into balance and focus on maintaining that balance.
This aspect of Yoga is often misunderstood, but balance plays a huge role in Eastern Medicine and the purpose of Yoga and similar meditative techniques is often no more than to achieve and maintain the level of balance that keeps our bodies healthy.
Yoga teachers will often talk about oneness and inner harmony, and this can be misinterpreted by people who lack a holistic understanding of what Yoga seeks to achieve. Simple the harmony that is achieved through Meditation and Yoga is a self-contentment or acceptance of oneself. This shows that the first step to becoming completely happy and healthy is to be content with yourself and your life.