Liu advocates that keeping in good health focuses on nourishing qi. On the basis of Wang Chong's view that people's longevity lies in "innate endowment", he further emphasized the ideas that "people in charge of life care about people" and "if people are short-lived, they should take care of themselves". This theory of "man is the master of life" shows that as long as we give full play to the subjective initiative of parenting, we can reach the realm of prolonging life. He attaches importance to the conditioning of qi, spirit, essence and shape, but especially emphasizes the maintenance of qi.

For the method of nourishing qi, he thinks that we should start from three aspects: regulating qi, nourishing qi and ventilation. He pointed out in "Su Wen Pathogenesis Collection, Qi Should Save Your Life, Original Theory" that: boasting and breathing, spitting out the old and absorbing the new, stretching the bear to pass the bird, guiding and pressing the stilts, so regulating qi; Calm your breath, hold your breath steadily, look inside the shrine, and your internal organs are very clear, so hold your breath; Ruling heaven and earth, following the principle of yin and yang, making love to each other, and using fire and water economically make them angry.

This nursing method can relax yin and yang, irrigate five internal organs and regulate qi and blood.