Those who, so far as it is possible, engage in the work of doing good to others by giving practical demonstration of their interest in them, are not only relieving the ills of human life in helping them bear their burdens, but are at the same time contributing largely to their own health of soul and body. Doing good is a work that benefits both giver and receiver. If you forget self in your interest for others, you gain a victory over your infirmities. The satisfaction you will realize in doing good will aid you greatly in the recovery of the healthy tone of the imagination. MM 105.3
The pleasure of doing good animates the mind and vibrates through the whole body. While the faces of benevolent men are lighted up with cheerfulness, and their countenances express the moral elevation of the mind, those of selfish, stingy men are dejected, cast down, and gloomy. Their moral defects are seen in their countenances.... MM 106.1
Invalids, I advise you to venture something. Arouse your willpower, and at least make a trial of this matter. Withdraw your thoughts and affections from yourselves. Walk out by faith. Are you inclined to center your thoughts upon yourselves, fearing to exercise, and fearing that if you expose yourself to the air you will lose your life; resist these thoughts and feelings. Do not yield to your diseased imagination.—Testimonies for the Church 2:534. MM 106.2