Ellen G. White, The Ministry of Healing, p. 241
The relation that exists between the mind and the body is very intimate. When one is affected, the other sympathizes. The condition of the mind affects the health to a far greater degree than many realize. Many of the diseases from which men suffer are the result of mental depression. Grief, anxiety, discontent, remorse, guilt, distrust, all tend to break down the life forces and to invite decay and death.
Disease is sometimes produced, and is often greatly aggravated, by the imagination. Many are lifelong invalids who might be well if they only thought so. Many imagine that every slight exposure will cause illness, and the evil effect is produced because it is expected. Many die from disease the cause of which is wholly imaginary.
Courage, hope, faith, sympathy, love, promote health and prolong life. A contented mind, a cheerful spirit, is health to the body and strength to the soul. “A merry [rejoicing] heart doeth good like a medicine.” Proverbs 17:22.
In the treatment of the sick the effect of mental influence should not be overlooked. Rightly used, this influence affords one of the most effective agencies for combating disease.