Sun Do practice is done while performing Danjeon breathing. For many, Sun Do is actually known as Danjeon Breathing. Danjeon Breathing is a term used by Grand Master Chung San to help beginners to understand Sun Do and its practice more easily. Performing the sets of postures while doing Danjeon Breathing is called Danjeon Haeng Gong and it forms the basis of the practice session during routine classes.

Basic Danjeon Breathing method is done as follows:

Focus all of your body and mind at Danjeon;

• Breathe only through the nostrils;
• Breathe deeply and naturally;
• Breathing should be as slow, steady and smooth as possible;
• The length of inhalation period and exhalation period should be the same (for beginners);
• Visualize breathing in the fresh life energy while breathing in, and visualize breathing out the toxic energy while breathing out;
• The lower abdomen should rise up while breathing in, and down while breathing out;
• The belly above the navel should not be moving and should be completely relaxed; and
• Use your focus, not muscle, to move the lower abdomen

Beginners should learn the exact location of the Danjeon, and how to do Danjeon Breathing from instructors.

It was clearly stated by the Grand Master that Danjeon Breathing could not be learned by merely reading a description from a book. Breathing is a very critical life mechanism and even a slightly wrong breathing practice could result in a grave physical problem or even a mental disorder.