Postures like the Three Circle Stance and San-Ti Stance are difficult postures to really relax into at first, especially if you are standing for a prolonged period of time. In fact, I think the most common mistake for beginners is that they try to
progress too fast for quick energy gains, only to injure the body both externally and internally, which creates setbacks and delays while recuperating. Like all internal training methods, standing practices have the potential to hurt you or to heal you, depending on quality of performance and how long you stand for.
I was taught to stand for no more than 3-5 minutes per practice session to begin with, and to yield the entire body to the downward pull of gravity, especially the hands, elbows, and shoulders. All of the joints should be relaxed as much as possible, and should all be curved or bent as a result. This includes keeping the hip, knee, and ankle joints curved and relaxed as well.
In this way, a feeling of great heaviness comes over the body, especially in the legs and feet. The soles of the feet may even feel a hot, burning sensation during the practice. And the shoulders will feel as if they are being weighted down from above, while the elbows will feel as if they are being pulled downward by weights suspended from them by cords. This initially feels uncomfortable and/or sore for most people, but will quickly pass as your whole body gets stronger when you continue to stand daily.
Similarly, the knees will feel as if they are supporting heavy weights placed on top of them, while the hips will feel as if they are being pulled downward by weights suspended from them by cords. Thus, all of the joints will have a rounded or curved appearance when observing your posture in a mirror, and every part of the body will feel heavy in response to the downward pull of gravity.
In order to maintain the posture for even 3-5 minutes in the beginning, some muscular effort will be needed in the legs, especially on the tops of the thighs, but not in the muscles on the back of the upper legs. Some muscular effort will also be necessary in the calf muscles on the back of the lower legs. Likewise, muscular efforts to hold the arms in position will be needed on the front surface of the upper arms (biceps), but not on the back surface (triceps). The muscles of the rear shoulders and tops of the shoulders bordering the shoulder joint will be engaged as well, but not the muscles of either arm between the elbow and the wrist.
When the proper posture of the body can be maintained in these ways, with the feelings described, for 3-5 minutes without break or pause once per day, then begin to increase the time by adding 1 minute of additional standing time to the daily practice each week until you can stand for 30 minutes or longer at each practice sesion. So, for example, when you feel comfortable standing for 3-5 minutes per day, without pain or soreness while standing, and without straining with painful trembling or spasmodic shaking, then only can you add another minute to the daily standing time. This slow and gradual development in the practice does alot to prevent injuries to the muscles, tendons, and ligaments, or straining injuries to any of the internal organs.
"Take it slow...your chi will grow. Progress too fast...you'll never last!"
Doc