When there is no mind, you are in yoga; when there is mind you are not in yoga. So you may do all the postures, but if the mind goes on functioning, if you go on thinking, you are not in yoga. Yoga is the state of no-mind. If you can be without the mind without doing any posture, you have become a perfect yogi. It has happened to many without doing any postures, and it has not happened to many who have been doing postures for many lives.