Save your nerves and breathe
Before breathing training, you need to save the nerves connected to dangeon. So, before going to danjeon, relax your neck, the cornerstone of the road.
Why is the neck holding on to the nerve going down to the danjeon? One of the reasons that the nerve in the back of the neck is stiff is that when the rectus abdominis muscle is pulled from the front, that is, when gripped in the dangeon, the muscles in the front of the chest are also pulled down. Later, even the muscles in the last clavicle are pulled down, and the muscles in the shoulders are pushed forward. People whose shoulders protrude forward like a bow are people whose dangeon is dead.
If the pull of the dangeon also pulls the shoulder, release it back to release the nerves that were pressed together in the back of the neck. If you start to loosen up like this, you may have problems with the back of your neck rather than the danjeon. If you focus on relaxing the back of your neck, the dangeon will be released on its own. In order for the knotted muscles to come to life, you need to rub them well. It's good to roll a bowling ball and massage your belly, and it's even better if you go into natural abdominal breathing.