"The most basic method of training is zhan zhuang. Zhan zhuang is an exercise common to many Chinese martial arts, including Taijiquan. Usually, the practitioner stands with the arms held as if holding a large ball. However, the zhan zhuang exercise can be practiced using any of the end postures of the Taiji form. During "standing" practice a static posture is maintained for a period of time while using just enough strength to maintain the posture. ... Benefits of zhan zhuang include deep relaxation, strengthening of the legs, and increased internal qi. The first requirement is to have a calm mind. This can be achieved in a number of ways - for instance, concentrating on the Dantian, paying attention to one's breath, or silently counting. Through standing practice, emphasis is place upon developing awareness of maintaining the most efficient and relaxed structural alignment necessary to hold the position. Prolonged practice, along with enhancing postural awareness and tranquility of mind, greatly develops the strength of the legs. When the legs are strong and can bear weight firmly, then the upper body can relax and sink down into them, making the top more flexible. ... Taijiquan requires lightness and sensitivity in the upper body. At the same time, the lower body should have a feeling of extreme heaviness and connection to the ground. This feeling is often compared to a large tree with deep roots. While the branches move and sway in the wind, the trunk is solidly anchored by its roots."
- Davidine Siaw-Voon Sim and David Gaffney, Chen Style Taijiquan, 2002, p. 106.