A posture should be such that you can forget your body. What is comfort? When you forget your body, you are comfortable. When you are reminded continuously of the body, you are uncomfortable. So whether you sit in a chair or you sit on the ground, that is not the point. Be comfortable, because if you are not comfortable in the body you cannot long for other blessings which belong to deeper layers: the first layer missed, all other layers closed. If you really want to be happy, blissful, then start from the very beginning to be blissful. Comfort of body is basic need for anybody who is trying to reach inner ecstasies