The quote "He who controls the mind, controls the qi" is from the Huang Di Nei Jing, also known as the Yellow Emperor's Inner Canon, which is a classic text of traditional Chinese medicine. If the mind is calm and focused, the qi will flow smoothly and healthily.
However, if the mind is agitated or distracted, the flow of qi can become disrupted, leading to various disharmonies in health (and therefore life).
The quote "He who controls the mind, controls the qi" emphasizes the role that the mind plays in regulating the flow of qi in the body.
It suggests that by learning to master our thoughts and emotions, we can influence the flow of qi and promote good health and well-being. This idea is fundamental to traditional Chinese medicine and is still widely recognized and applied today.