Intention leads movement and energy. Yi leads the Qi as though it was pulling this water like energy from point a to point b. It should never be focused on the Qi as that will cause stagnation.
If you focus on a single point; pick the tip of you finger, let you mind focus and you feel a range of sensations, most commonly heat. There are many teaching that when the mind (yi) is talked about it is more akin to the Buddhist sense of Heart/Mind; without confusing things this is a little like the western concept of Spirit…but not Shen the Chinese version…Having confused things, now think of this as soft thought, not the grasping desperate chit chat of you waking self but more like the silent witcness of the soul who is ever present in the places between this and that. That moment of breathing out, the connection and letting go of doing and being single pointed connected to that moment. Like sitting on a chair, you do you sit and when you connect there is that “moment” Breathing is the same, when connected to the movements within Qi gong.
In Tai chi and Qi gong breathing while you are moving creates a union within the body. The breath must never chase the movement ; if anything it should follow your intention leading the movement. The general rule of thumb in Yang style Tai chi and many forms of Qi Gong is that an outward, rising and upward movement is folowing the inhalation. A sinking, closing ,inward & downward movement is on the exhalation. As those familiar with yoga will already know, there is a release and “moment” on the exhalation. This can be see as a Yin empty yielding where as the inhale is an assertive Yang movement, never forgetting that Yin Yang theory is all about comparative contrasts.
There are two types of breath that are of interest to the beginner:
Abdominal Breathing (Buddhist Breathing)
Children do this naturally, where as some adults retain this skill, most loose it to a tight chest breath, perhaps indicative of our stressful initiation into a society full of anxiety. It’s ok though – we can relearn it!
When we breathe in imagine the breathe descending deep into your lungs and past your diaphragm (not possible btw!) Place you attention on the Dantien and allow your breath to expand you belly as you relax the Huiyin point (see diagram) by feeling it descend.
When you breathe out you contract you belly and contract and pull up the huiyin point. On the inhale and exhale try and stop your chest from rising or falling.
Reverse Breathing (Daoist Breathing)
As you breathe in you extend the diaphram down while drawing up the Huiyin you withdraw the abdoman and imaging the Mingmen point on the back is also contracting. your chest should slighty expand.
As you breathe out relax the huyin, feeling it “release downwards, expand the belly as the back is released outward and chest slightly sinks. Qi moves towards the inside of the body as you inhale, nourishing your organs; and as you exhale the Qi moves outwards to your skin
Daoist breathing https://www.consciouslifestylemag.com/dantian-daoist-meditation/
Brass basin https://zenwellness.com/qigong-breathing/