Proverbs 17:22

A merry heart doth good [like] a medicine
Does the body good, makes it healthful and vigorous. Cheerfulness of spirit has a great influence upon the body, and much contributes to the health and welfare of it; see ( Ecclesiastes 9:7-9 ) ; and especially a heart full of spiritual joy, peace of conscience, flowing from the blood of Christ, joy in the Holy Ghost, a rejoicing in Christ Jesus and his righteousness, and in hope of the glory of God, much affect even the outward man. Or, "a merry heart makes a good medicine" ^F24; it is a good medicine of itself; raises the spirits, invigorates the body, and fits it for service and business: or, "does a medicine good" ^F25; makes that operate kindly, and to a good purpose: or, as Jarchi, makes the countenance shine well, makes a serene countenance; which Schultens approves, and, from the use of the word in the Arabic language, confirms; but a broken spirit drieth the bones;
a spirit broken with sorrow, whether on spiritual or temporal accounts; as it weakens the nerves, it dries up the marrow in the bones, and emaciates the body, and reduces it to a skeleton: the joy or grief of the mind, those passions of the soul, have a very great influence upon the body, either for its good or hurt.