Although the term 'Yoga' is popularly known as a physical set of exercises and poses, the actual meaning of 'Yoga' is quite different. Yoga literally means union. To practice 'Yoga' means to practice union of consciousness.
The exercises and poses known as Yoga are traditionally called asanas which are used as preparation for meditation. Asanas are a subsection of Hatha Yoga which is a subsection of the Vedic Wisdom called Yoga.
What exactly is the 'union' experienced through Yoga?
Through meditation anyone may experience the underlying reality of life which is transcendental to all sensory experience. This transcendental, unbounded experience of pure consciousness may be known as union with the Self—the innermost field of existence at the most silent level of the mind and of nature.
How to practice Yoga?
Through correct meditation the mind will experience deeper and deeper levels of experience, until you transcend thought completely and experience the silent state of pure consciousness at the source of thought. The process of transcending is natural to the human mind because the mind is attracted to the charm and silence of the deepest level of consciousness which is called, in Sanskrit, 'sat chit ananda' or unbounded bliss consciousness.
Research has shown that specifically one method of meditation, the Transcendental Meditation®
technique, actually produces the unique neurophysiology and brainwave coherence that is associated with the experience of Yoga. Along with the settled state of awareness during TM practice, the meditator experiences profound healing rest in the body. This combination of experiences produce a broad range of benefits to the brain, mind, health and relationships
Why don't other meditation techniques work?
Unfortunately, most meditation techniques involve either concentration or contemplation, both of which keep the mind on the active level of thinking so they do not produce that transcendental experience of union which is Yoga.