To increase the immune system in the body, the Parasympathetic neuro-system must be excited for the brain to produce Serotonin. 

 To excite the Parasympathetic neuro-system, it is required to have your mind being peaceful, calm down, and think nothing or only one thing. If your head is busy to think this and that, you can't calm down your mind. 

 Generally, meditation with Lotus posture and closing eyes, is known as a very effective way to excite the Parasympathetic neuro-system. 

But more powerful and effective way is to directly push and pull the bundle of Parasympathetic neuro-system, which is surrounded by the Pelvic bones safely. The only way to excite Parasympathetic neuro-system physically, is to breathe deeply by lower abdomen, which is Danjeon. 

 Sundo has created and organized the way of Danjeon breathing, since 9,700 years ago. And Sundo has unique way to calm down your mind, and think only onething. When we practice Sundo, we hear the background Sundo music that has special Rhythm and tempos. No other one, including Yoga, has such Rhythm or tempos to breath. 

It guides us to breath along with the music and tempos, and to concentrate on one thing - well, it will be appeared to everyone differently. To the beginner, we recommend to think a fish swimming in the pot - simply no meaning but moving back and forth repeatedly. But to the high level trainees,they can see their universe in their mind which is the theory of their life. 

Sundo practicing is good for your health, because it helps your body to increase the immunity power.