Introduction

This verse was a real challenge. The macro-level, philosophically oriented translations and interpretations fell flat—something about it kept eating at me. I dove headfirst down the rabbit hole, expanding my lexicon of Daoist alchemical terminology to overlay with my training, and eventually, it clicked. I could suddenly parse troubling sentences and obscure paradoxes resolved into clear instructions. 

This verse discusses most of the critical transition points and alludes to the technical details of Daoist meditation. Perhaps you can find some details here to support or begin your practice.

Translation

If one is deficient in
  Great Skill,
  breath unbroken.

If one is overflowing in
  Great Fullness,
    breath “no extremes.”

If clumsy in skill…
If stammering in revealing…
If bending in uprightness…

Overcome “cold” with “fire.”
Overcome “heat” with “stillness.”

Stillness and clarity put the world in order. 

Commentary

If one is deficient in
  Great Skill,
  breath unbroken.

Great Skill refers to the initial phase of the meditative journey where one learns to still the mind, invert the breathing (meaning the stomach expands on the inhale), remove tension throughout the body, hold the gaze steady, turn the senses inward, and such things. The point of this practice in Daoist Alchemy is to restore, harmonize, and refine the three treasures of essence, breath, and illuminating consciousness (the three treasures) in preparation for the energetic work to come. 

While many techniques are involved in this process, the text here points to one in particular: breath unbroken. Breath unbroken is not necessarily a persistently smooth breath that immediately exchanges from inhale to exhale, though this is the eventual state. This process may require restraining the breath between inhale and exhale. The central point of “breath unbroken” is recognizing that the breath is the go-between for the “heart” and the “spirit.” 

The heart is another name for the container (subject), the spirit refers to that which goes out and illuminates all the contents (objects), and breath is the bridge (self-awareness). The “unbroken breath” is the process of yoking the spirit to the heart - i.e., not letting the discursive mind jump around according to sensory impulses but having it squarely focused on the experience of being conscious. 

Just doing that over and over again will lay the foundations for the coming stages, notably regenerating essence ( 精 jīng， i.e., energetic vitality) to refine it into Breath, this time with a capital “B” that has a meaning more akin to prana, or Life Force (炁 qì instead of 气 qì ). As the breath becomes Breath, it smooths out and becomes quite imperceptible while the experience of Breath in the body strengthens.