The two below quotes do a great deal to explain this conceptualization of xing and Ming in daoism. Huang yuanji believed that xing (our true nature) is the same as the open sky and that Ming, our life energy is borrowed from the sky as the oxygenated breath we bring into our bodies during respiration.
The huangdi yinfu jing is the first classic to clearly lay down self cultivation as the practice of mastering the movement of the heavens through observation.
Below I will provide quotes from both sources to build my argument that the true xing and Ming practice of daoism is mainly based around observation of emptiness and the breath and that they are not separate, nor do they require special minor practices outside of meditation to achieve their value.
Dao de jing chan Wei:
Heaven and earth give birth to humanity,
Stealing the air and establishing life,
Stealing the great principle and establishing nature.
The principle and air are originally mixed together as one. Nature and life do not part from one another.
Huang di yinfi jing:
Observe the Dao of the heavens,
Grasp the movement of the heavens,
Your work will be complete.