Yin qi, the opposite of yang qi, refers to the shady side of all things.
1. The changing of the four seasons and the changes of the five elements result in climates characterized by chill, heat, dryness, damp, and wind.  They affect all living things in nature, causing them to be born, grow, flower, wither, and hibernate.
2. Every person has a liver, heart, spleen, lungs and kidneys, known as the five intemal organs. The emotions of joy, anger, sorrow, anxiety, and fear come from the qi of the five internal organs.
3. Everyone should pay attention.
Also learn more in the article Internal Impairment.