When someone reaches 100% of Cheng 12 of a level, they must undergo Chi Breathing to realign their chi.
When one is undergoing chi breathing, they will be killed instantly by any attack, so it is wise to do this only in a safe area, such as a town.
Chi Breathing is a simple exercise. A diagram will appear with white, black, and blue circles. These will be traced by a glowing orb. When the orb is over a white circle, you left-click, when the orb is over a black circle, you right-click, and when it is over a blue circle, you click with both buttons simultaneously.