When we sit in a chair, our hips should be as far as back in the chair as possible. Head, spinal column, Shoulder and hips should be in straight line and erect. Legs should touch the ground and not in hanging position. Thighs should be in horizontal position. While we read, the book should be on the table but the book should not be too away or near the eyes. The approximate distance between book and eyes should be at least 30 cms. If we do not follow this rule, then eyesight problem may occur.