Zhang Sanfeng's study of Taoism's Taiji and Yin and Yang is the theoretical basis of Neidan's vitality. Ideologically, he advocated "double cultivation in life", combining practice with self-cultivation. Follow the natural laws of the human body, alternating motion and static, with both form and spirit. In particular, it highlights the idea of being quiet and natural, weak and indisputable, and free and easy.
Under the guidance of this thought, Zhang Sanfeng later founded the Tai Ji Chuan method, which is not only a method of self-cultivation and leading to the avenue; It is also a martial art for self-defense.