After an individual has cancer, the mental factor is very important. Under the influence of the old concept of “cancer is an incurable disease”, individual patients always feel that everything is over, they do not think about their food and tea, they are bedridden, and even refuse to take medicine and treatment, as a result, their disease deteriorates quickly and they die. On the contrary, many cancer patients can treat the disease correctly, be optimistic, actively cooperate with treatment, follow medical advice, enhance nutrition, pay attention to regular life, strengthen exercise, and try to mobilize the body’s resistance to disease, so that the disease can be controlled, improve continuously, and finally be cured. Although the evidence is not sufficient, a positive mental state can improve the patient’s ability to live with the disease and enhance the effectiveness of the medicine. Fear of cancer, anger, loss of self-esteem, isolation, etc. can weaken a patient’s will to live, while a desire to live, courage, hard work, patience, and trust in medical personnel and family can strengthen a patient’s will to live. The right attitude after an illness is: to realize that one is living in reality, not in memories of the past; to set reasonable and realistic goals for oneself, the society and the family; to acknowledge the new problems in one’s life, to recognize them objectively, and to be willing to solve them together with others around one; to try to clear oneself of negative emotions and pessimistic thoughts; to take the initiative to do what one can do; and to be willing to do what one can do after treatment. In the treatment, we should be an active partner and see ourselves as an important member of the whole medical process, even when we are in critical condition, and we should make ourselves feel that there is still potential to be explored both physically and mentally, so that we are always in a state of optimism.