Proverbs 17:22 A merry heart doeth good like a medicine: but a broken heart drieth the bones.
God promises good medicine and healing powers, if you have a merry heart. We know how a positive outlook inside affects the health of the outside, and we are told that a negative spirit brings sickness and impedes healing. There is something real about “psychosomatic” illness. We can make too much of it, but we can also make too little of it. No one truly understands the connections between the body and the soul, but there is something going on there. The sayings about “mind over matter” and “it’s all in your head,” have some truth, but it isn’t really helpful.
We can just take God’s Word as truth, and believe that an optimistic, positive and joyful soul affects the body for good. We can also understand that a negative, depressed spirit negatively affects the body.
But you can’t just tell a sick or hurting person to just “cheer up.” It doesn’t work; it just makes him feel worse. However, you can tell him the Good News of the Gospel in a meaningful way. Anything else is only Law, which beats him down further into guilt, shame, and despair.
Only the gospel has the power to make a merry heart. A heart filled with the life and the love of God can do good like a medicine. Speak gospel words to yourself and others to make the heart merry; then let the merry heart do its work.