Sit comfortably on a chair. Rub your hands together until they feel warm. Close your eyes and cover them lightly with your cupped palms. Avoid applying pressure to your eyeballs. Your nose should not be covered. Make sure no light rays can enter your eyes though gaps between your fingers or the edges of your palms and nose. You may still see other lingering traces of colors. Imagine deep blackness and focus on it. Take deep breaths slowly and evenly while thinking of some happy incident, or visualize a distant scene. After you see nothing but blackness, remove your palms from your eyes.
