"Moving Meditation includes: (1) Mind (Yin), and (2) Movement (Yang).
"In moving meditation, although the physical movements stimulate the body, the mind should remain calm so that it can lead the Qi smoothly and calmly. Therefore, the motion of the physical body is Yang and the calm mind is Yin.
"(1) Mind: a) Qi Condenses for Defense or Jin Storage (Yin), and b) Qi Expands for Attack (Yang).
"When your mind is on defending or storing Jin for attack, it will lead the Qi inward. The body will feel cold, and the Qi of the body will condense into the marrow; this mind is therefore classified as Yin. This condensing process is usually coordinated with inhalation in reverse abdominal breathing, and this inhalation is also classified as Yin.
"However, when your mind is on an attack, it will lead Qi to the surface of the skin and to the limbs to energize the muscles to a higher level of efficiency. When this happens, the body feels warm and the energy of the body feels like it is expanding. Therefore, it is classified as Yang. Normally, this offensive process is coordinated with exhalation in reverse abdominal breathing, which is also classified as Yang.
"(2) Motion: a) Withdrawal and Defense (Yin), and b) Expansion and Offense (Yang).
"In the movement of Taijiquan, the withdrawing and defensive movements are Yin, while the expanding and offense movements are Yang. When you reach the level where the Yi, Qi, and movements are united, you have touched the essence of Taijiquan.
"Naturally, the Yin defensive movements of Taiji can again be divided into Yin and Yang. For example, a completely defensive withdrawal movement is a Yin defense, whereas, if the withdrawal is used to set up an offense, it is considered a Yang defense. This is because the Yi stays Yang, even though the movement is Yin.
"Similarly, in the Yang expanding, offensive movements, if the offensive movement is purely for striking, then it is Yang. However, if the offensive movement is used to set up for a retreat, the Yi is Yin, so the offensive movement is strategically Yin." *
* Dr. Yang, Jwing-Ming, The Essence of Taiji Qigong