This is a good basic introduction to that branch of Chinese medicine known as health preservation. Covering regularity of lifestyle, eating habits, sexual moderation, rest and relaxation, self-massage, exercise, qigong etc. It may take much of one's lifetime to reconcile and integrate these opposites, but then patience is a virtue.
Profit is to be compared with the sowing and cultivating of plants.
Before anyone realises it, the shoots begin to appear. Therefore, when regulating the body and nurturing its life, give care to the little things. Even a slight profit is not be considered unimportant and left uncultivated, nor is a slight loss to be considered harmless and left unblocked. If you can appreciate it when it is only a promise and perfect it when it becomes evident, you are close to knowing the divine process. That is why those who know recipes for sexual intercourse say that only those recipes can lead to immortality.