Chinese medicine explains, “The 100 diseases start with wind,” which means that most illnesses can start from internal chi flow gone astray and that “gone astray” is often the result of “external wind” invasion (external chi) entering your body.
Have you ever been into an air conditioned elevator on a hot day, or sat directly in front of an air conditioner in a room and then come down with a cold, a headache or the sniffles? That result is what Chinese medicine calls a “wind invasion,” meaning that this “external wind” was so strong that it entered into your body and made you sick. You become sick because of a chi invasion into your body rather than because of a poor immune system
In general, disease is perceived as a disharmony (or imbalance) in the functions or interactions of yin, yang, qi, xuĕ, zàng-fǔ, meridians etc. and/or of the interaction between the human body and the environment.
When the flow of Qi is unimpeded there is harmony, balance, and good health. When there are Qi blockages, too much or too little qi, there is an imbalance which can lead to disharmony and disease.