Daoyin is a method of training which was originated in northeastern Asia, with distinct changes through the seasons. Therefore, the methodology for training is not focused on static moves, but was rather developed around endless changes to the movement.
Daoyin principles begin from the simple fact of non-movement resulting in problems, and movement to result in problem-free health. Regarding this notion, the following set of old Chinese characters can best explain.

Ho-Shu-Fu-Dou, Liu-Shui-Bu-Fu(戶樞不蠧, 流水不腐): door hinge shall not be eaten by moth, and water flowing shall not become undrinkable.
This phrase is metaphorical of the Daoyin movement, to move the limbs on the outside, to stimulate internal change and effects, and thereby encouraging communication of blood & energy to the internal organs and bones to cause change on the inside as the way of Daoyin.

Tong-Zuo-Bu-Tong Bu-Tong-Zuo-Tong(通卽不痛 不通卽痛): Meaning, with circulation, there is no pain, but without circulation, there is pain.
This saying means that through proper movement, with proper circulation of Qi, there would be no pain or disease.

If one were to choose the biggest difference from Daoyin to any number of other martial or disciplinary arts, it would be the point of disciplining each of the movement. Daoyin training involves not so much in keeping the body in one particular attitude, or making the upper body strong, but in not tiring of moving the four limbs according to regulations, to continually move in discipline for each moment to discipline physiological effects and internal energy management. In tempering of movements, at the core part of the human body are the joints. In movement, it is because the most animated part are the joints in the whole body.

The very phrase Huan-Gu-Duo-Tai(換骨脫胎) originates from the Daoyin training system of joint-centered movement reinforcement. 'Transform the Huan-Gu, the skeletons, for Duo-Tai, or metamorphosis' is the meaning. Here skeleton means a methodology to master the manner of movement and Qi redirection for opening and closing of the joints. Tai(胎) means the habitual state of non-change and non-circulation, of body and emotion and mind for the status-quo. Duo-Tai(脫胎) then would mean putting off these static habits. Or, to be free of the habits which limit me and become new, through the changing out of the skeletal framework.

In the disciplined movements of Daoyin exercise, there would obviously emerge a rule for proceeding according to the principles of motion. he principle of motion is none other than the laws of Yin-Yang, which is Tian-Li(天理), the will of Heaven already granted to the existence of man. To bend one side will cause the other side to become straightened, inhaling will naturally result in exhaling. This law of yin & yang influences the minute workings of organs, emotions, even to the use of reasoning. If only we were to live according to the manifest laws of yin & yang, everyone would always be healthy, but through actions in our daily life which contravene the laws of yin & yang, and through the hardening of these habits, we gradually come to lose our state of health.

Therefore, Daoyin movements proceed by necessity in obedience to the rules of yin & yang, in helping to return to the original state of harmony. This is the reason why Daoyin moves turn the body in various angles and forms, stretches and bends the arms and legs, contracts and extends. In this process the human body qi force also rises and falls, splays then merges, corkscrews. Conclusively, leads our bodies to that state where both yin & yang are possible. Movements which tilt to either yin or yang, one side, will surely bind the mind & body in a state of imbalance, so that a traditionally well choreographed Daoyin never fails to keep to the rhythm of 'yin' once then 'yang' once, of Yi-Yin-Yi-Yang(一陽一陰). As the depths of Daoyin is approached, ability beyond simply returning to the innate state of yin-yang harmony is cultivated, to adjust and use yin & yang befitting the circumstances.

Daoyin is not a system of training to simply improve external bodily functions through external movements. Using external motion as a tool to extract the effects of qi, by necessity, to breathe vitality into the organs, even to the articulating joints. To achieve this, the three domains of the human body, namely the arms, legs and the torso must be combined in the actions of the movements. This is called the Coordinated Effect of Three Body Parts(三合作用).

This working of qi from the triad effect is as the instantaneous appearance of a shadow, from the elements of a flame, an object, and a white wall. Just as for any of the three, the flame, an object, or the wall to disappear, there would not be a shadow to be formed, so also in Daoyin movements, the influence of Qi circulation would be impossible without the triad effect.

For even a group of people practicing the same Daoyin will reach different depths of mastery, depending on their understanding of the triad effect of each motion. Since this triad effect of each movement possesses uniquely operating qi effect of each, proper execution of the move can result in each obtaining different efficacy, to command even the movement of internal autonomic organs. So, each motion contains a secret for Qi operation, and the question of secret teaching(秘傳) in Daoyin depends on the preservation of this triad effect for posterity.

Daoyin is training for self control through self practice. Conversely, An-Mo(按摩) is a method of applying the efficacy of Daoyin to another.
Just as Daoyin is divided between techniques of handling Qi versus Shape, the same holds true in the art of applying it to another. For in An-Mo, An(按) is the method for handling another person, and Mo(摩) is the method of handling its shape. In the Orient, traditionally Daoyin, together with Anmo formed a pair as a healing art, where the achievement of depth through self training of Daoyin formed an important part of understanding Anmo.