The process (connecting the upper thighs and the perineum) is difficult to describe, because the fundamental is the occurrence of consciousness, and how the occurrence of consciousness resounds in the stretch of the fascia. The lion is totally relaxed, and enters into motion totally relaxed, because the action comes out of feeling generated by the impact of consciousness on stretch. The lion does not intentionally stretch, yet the presence of stretch is evident in the relaxed, tenacious movement of the lion.
I have learned to be very cautious when anyone says to do something, and especially with regard to the breathing. My preference is instruction that describes reality and emphasizes self-surrender, not because an intentional approach is wrong (can’t get away from it, really), but just because what I needed to learn myself was how to let it all fall together. Relearn the way I hold myself upright, the way I set mindfulness in front, from the inside out.
When we let go of our minds and cast aside our views and understandings the Way will be actualized. One sage clarified True Mind (Reality) when he saw peach blossoms and another realized the Way when he heard the sound of tile hitting a bamboo. They attained the way through their bodies. Therefore, when we completely cast aside our thoughts and views and practice shikantaza, we will become intimate with the way. This is why I encourage you to practice zazen wholeheartedly.