In martial arts training, to cultivate more qi and have better qi circulation is not enough. One must manipulate this qi to fuel martial arts techniques. The complete work in martial arts training often involves two steps: active and inactive exercises or internal and external exercises. The methodology consists of first accumulating qi, then converting the qi into NeiJing or internal power by coordinating it with martial arts techniques. This training methodology, which involves quick and sudden physical movements, is called kaigong by some and Fa Jing by others. It is the combination of quick and sudden movements with intent and qi. The practice of this method is often guided by the principle called "Six Harmony Theory" among Chinese martial art practitioners. The Six Harmony Theory is divided into the Three Internal Harmonies and the Three External Harmonies. The three internal harmonies are the mind in harmony with the intent, the intent in harmony with qi and the qi in harmony with the power, to guide one in the neigong training. The three external harmonies are the shoulders in harmony with the hips, the elbows in harmony with the knees and the hands in harmony with the feet, to guide in the kaigong training. In other words, the method of neijing development involves special breathing techniques combined with a goal specific physical movement so that the result of this execution is concentrated and powerful. Because this execution involves intent, qi and power, the result is often so powerful that it is difficult for the spectator to believe.

Throughout neigong training, the practitioner slowly, improves and develops his body for optimum performance, resulting in good muscle tone, a body full with lively neijing or internal power and without stiffness, and with all brute force removed. This neijing is the result of neigong and kaigong trainings guided by Six Harmony Theory. When one applies this neijing to the body, it is soft like cotton if the body is relaxed. When the body is tense, it is hard like steel.

From a scientific perspective, one can understand neijing as the force resulting from blood and qi circulation. From an application perspective, it is guided by the intent. The qi and the blood flow in a specific direction, coordinated with a specific movement, and delivered to a specific point. Or, the qi begins unfocused, and becomes more focused and finally, concentrated. When the qi follows the intent's instruction into a specific area of the body, and then is delivered outside the body by a quick and sudden physical movement, the qi becomes neijing. It is capable of causing serious injury to the opponent. Of course, this whole procedure must involve some muscle contraction; but the primary component comes from the intent's function in guiding the qi and blood. Among martial art practitioners, it is often said " It is easy to train kai Gong. It is difficult to train Nei Gong". The neigong training is difficult because of qi's accumulation and circulation. It is easy in kaigong training because of the tangible factors. One can see, touch, adjust, and easily master the principles, methodology and theories. On the other hand, qi accumulation and circulation are intangible. One cannot see or touch qi and awareness of it depends on one's sensitivity/awareness which is difficult to experience for some people. Therefore, neigong training is difficult. Our cogitation is very active. Generally, there are many thoughts appearing in the mind at the same time. The second thought arrives before the first thought disappears. It is very difficult to stop and be quiet. In neigong training, tranquility is the first requirement. It is only in a tranquil condition that one is able to concentrate on the intent to have the qi and blood circulate inside the body. Therefore, concentration determines the quality of neigong training. If one has many thoughts and is not able to concentrate, the qi will be scarce and it will be difficult to unify and circulate it. The result is not very good. To improve one's concentration, one must have patience and remove all stimulants and temptations, one must spend a great deal of time practicing the inactive exercises or meditation exercises. Some of the more common meditation exercises are sitting meditation or standing meditation. The goal of sitting meditation is to cultivate the mind, qi and spirit. The goal of standing meditation is to condition the body, and improve qi circulation and accumulation. The goal of this neigong training is to have better qi circulation so that it can be accumulated, unified, mobilized and coordinated with physical movements to produce more neijing. In qi manipulation, the intent is the most important ingredient. The stronger the intent, the outcome is greater. Therefore, all advanced martial arts training often emphasizes cultivation of the intent. The work of intent cultivation is not a day's work, it is a daily work. It is a yearly work. Therefore, one must have confidence, patience, persistence and perseverance in training.