黄帝曰∶外不劳形于事，内无思想之患，以恬愉为务，以自得为功。形体不敝，精神不散，
可寿百数矣。
彭祖曰∶凡人不可无思虑，当渐渐除之。身虚无，但有游气。气息得理，百病不生。又曰∶
道不在烦，但能不思衣，不思食，不思声色，不思胜负，不思得失，不思荣辱，心不劳，神不极，
但尔，可得千岁。
庚桑楚曰∶全汝形，抱汝生，无使汝思虑营营。
《灵枢》曰∶思虑怵惕则伤神。神伤则恐惧自失，皮烂脱肉，毛悴色夭。
书云∶思虑过度，恐虑无时，郁而生涎，涎遂转升而不降，为忧气劳思五噎之病。思虑则心虚，外邪从之，
而积气在中，时减于食。又云∶思虑伤心，为吐衄，为发焦。谋为过当，饮食不敌，养生之大患也。
诸葛亮遣使至。司马不问戎事，但以饮食及事之繁简为问。使曰∶诸葛公夙兴夜寐，罚二十
以上皆亲览焉，饮食不数升。懿曰∶孔明食少事烦，其能久乎？后果然。
张丞节云∶劳，经言瘵证，有虫，患者相继，诚有是理。只譬如俗谈不娩事，人害相思也，
与一女人情密，勿经别离，念念不舍，失寝忘餐，便觉形容瘦悴，不偿所愿，竟为沉 。
士人有观书忘食，一日有紫衣立前曰∶公不可久思，思则我死矣。问其何人。曰∶我谷神也。
于是绝思而食。是故盖思则气结，伏热不散，久而血气俱虚，疾至夭枉也。
The Yellow Emperor said: Externally, do not exhaust the body through affairs; internally, have no worries of thought. Make tranquility and joy your pursuit, and self-contentment your achievement. If the physical form is not worn out and the spirit is not scattered, one can live to be a hundred years old.
Peng Zu said: It is impossible for ordinary people to be without thoughts and considerations; one should gradually eliminate them. When the body is empty and void, only wandering Qi remains. If the breath is regulated properly, a hundred diseases will not arise. He also said: The Dao is not complicated; as long as one does not think about clothing, food, sounds and colors, victory or defeat, gain or loss, honor or disgrace, the heart is not labored, and the spirit is not exhausted, merely by doing so, one can live to be a thousand years old.
Gengsang Chu said: Preserve your form, embrace your life, and do not let your thoughts and considerations be in constant turmoil.
The *Ling Shu* (Spiritual Pivot) states: Thoughts and fears injure the Shen (Spirit). When the Shen is injured, there is fear and loss of self-control; the skin decays, flesh wastes away, hair becomes brittle, and the complexion turns dull.
Books record: Excessive thinking and constant worry lead to depression and the production of phlegm-fluids (Xian). These fluids ascend but fail to descend, causing disorders such as the Five Sieve (Wuye) diseases attributed to sorrowful Qi and laborious thoughts. Thinking weakens the Heart; external pathogenic factors then invade, causing stagnant Qi to accumulate in the middle Jiao, leading to reduced appetite. It is also recorded that excessive thinking damages the Heart, resulting in hematemesis (vomiting blood), epistaxis (nosebleed), and dry, brittle hair. Over-planning and dietary intake mismatched with physical capacity are major hazards to health preservation.
Zhuge Liang sent an envoy. Sima Yi did not ask about military affairs but inquired only about Zhuge's diet and the complexity of his tasks. The envoy replied: Lord Zhuge rises early and sleeps late, personally reviewing all punishments of twenty strokes or more; his food intake is less than a few sheng. Sima Yi said: Kongming eats little and has burdensome affairs; can he last long? This indeed came true later.
Zhang Chengjie said: Exhaustion, referred to in medical classics as Zhai syndrome (consumptive disease), involves parasites, and patients die in succession; this is indeed plausible. Consider the common talk of "lovesickness." A person suffering from lovesickness, who is intimately attached to a woman and experiences separation, constantly cherishing memories and forgetting sleep and meals, will feel their appearance become thin and emaciated. Unable to fulfill their desires, they eventually fall into severe chronic illness.
A scholar once read books to the point of forgetting to eat. One day, a man in purple robes stood before him and said: You must not think excessively; if you do, I will die. The scholar asked who he was. He replied: I am the Gu Shen (Grain Spirit). Thereupon, the scholar ceased excessive thinking and ate. Thus, it is generally believed that thinking causes Qi stagnation, latent heat fails to dissipate, and over time both Qi and Blood become deficient, leading to disease and premature death.