Tai Chi is considered a form of mind/body exercise, with many benefits for mental health and development, as well as Metarobic benefits for the health of the body. See the Mind/Body Research Page of the Metarobic Institute for a brief overview of related research. I recently put together the below for a Meetup group, related to Tai Chi as a form of Kung Fu, rooted in Zen elements which developed hand in hand with the martial arts in Japan. The article discusses a Zen Koan (Riddle) used to stimulate insight on what constitutes a powerful life.
 
Warrior Koan 100: FREEING THE GHOST
 
Aside from what I have learned from my teachers and own training, there are many great resources on the traditional elements of the martial arts, including Tai Chi, as Zen training. Following is the last Koan in Trevor Leggett’s “Samurai Zen: The Warrior Koans,” and how it applies to life and Tai Chi as a mind/body practice. In the early development of Zen, the Samurai made such swift progress, that an early Zen teacher noted that monks might as well give up meditation and study the Way of the Sword. There is something about the Martial Way (Budo, Wu Tao), which particularly focuses the mind. This applies to Tai Chi as much as the Way of the Sword, or any other traditional martial art. Following is Warrior Koan 100: FREEING THE GHOST.
 
FREEING THE GHOST (paraphrased)
Yorisha’s meditation was on the Kegon sutra (in the year of 1374):
 
“If one would know all the Buddhas of the three worlds,
Let him see the nature of the dharma, that all is the creation of the mind alone.”
 
Making no progress, he sat unaware, as the meditation hall caught fire. He perished in the flames. His ghost returned, chanting repeatedly; “All the Buddhas of the three worlds,” until the head of practice (tanto) Karashigawa gave a great shout “Reverence to Buddha Yorisha!” Yorisha promptly vanished.
 
A series of questions follow this Koan, asking the nature of the Buddhas of three worlds; the dharma-world; what is proof of ‘mind alone;’ and what is meant by dharma-world nature being the creation of the mind alone. The final question asks the meditator to set the ghost of Yorisha free “quickly, and show the proof.” There is also a section relating back to another Koan. But to keep it short, I will focus on the Kegan sutra directly, which will give useful background for answering the Zen master’s questions.
 
Buddha literally translates as “enlightened one,” and can apply to all who have achieved realization regarding the nature of Reality and Being (and actually Act on it, transcending it so to speak). The first of the three worlds is the “world” of base desires (Kamaloka) – lust, gorging, greed, fame, arrogance, hate, envy, self-pity, etc.  Somewhat similar to the concept of the seven deadly sins in Christianity. The second “world” is the world of form (Rupaloka), the physical practices (such as sitting meditation, Tai Chi, Kung Fu, etc.) which can lead to freedom from base desires and negative social influences. To become “the uncarved block” mentioned in Taoism. Which in turn can lead to enlightenment, which relates to the third world (Arupaloka). This third world is without form, the “Tao which cannot be told.” It is often seen as a spiritual existence beyond life, but from the Zen perspective, can also be seen as living true to your essential nature, before “you” were formed by peer pressure, social norms, and parental and teacher influence (as stated in a Zen Koan, to discover “your original face, before “you” were born” – or pushing it back one generation, “your original face before your parents were born).
 
The early Zen Masters had a clear concept of the influence of behavioral psychology on life, over a thousand years before Skinner. Zen also includes many elements of humanistic and psycho-analytic psychology – The Hierarchy of Needs has many parallels in Zen, and the Id, Super Ego and Ego are similar in many ways to the three “worlds.” Much of socialization is beneficial, and helps shape a person in good ways. But many forms of peer pressure and socialization can also be negative and destructive, twisting us in ways which can lead to depression, stress and even suicide. Zen/Mindfulness Based Practices are designed to increase awareness and freedom from the negative social influences and trauma in our lives (which can be of great benefit to those suffering from posttraumatic stress disorder, as well as other forms of personal trauma).
 
The goal of Tai Chi as a Zen practice, is to develop awareness and insights necessary to free you from destructive desires and emotions which sabotage life, using the mental strength and discipline which comes from training (including form training), and using form (the second “world”), to become an unlimited being free from destructive desires and emotions, with clear understanding of self and others, and how to live a powerful life.
 
By seeing the nature of the dharma (teachings/life principles), through meditation and flashes of insight (Kensho - which can occur during moving forms of meditation, as much as during sitting meditation), one comes to realize that the way we live our lives (even our jobs and relationships, as well as our fears, insecurities, anger and other issues), are in many ways the creation of our own mind – how we respond to the stimulus of life and those around us. Realizing this, one can come to mastery over the three worlds of destructive desires, right form (The uncarved block), and True Existence (The Tao which cannot be told). Many spiritual practices consider the way we live our life now as having an impact on our life after death, and relates to the purpose of life and the nature of existence.
 
It may be odd to think that martial training (whether Tai Chi, Kung Fu, Swordsmanship or other art) was considered so important in the early development of Zen, but when you think about what a fight it can be to overcome past trauma, insecurities and doubt, and the potential negative and destructive influences of others, in many ways it makes sense that the early Samurai united the Way of Zen with the Way of the Sword. Action is the only way to “show the proof.”