Trust in the LORD with all your heart and lean not on your own understanding; in all your ways acknowledge him, and he will make your paths straight.  Do not be wise in your own eyes; fear the LORD and shun evil.  This will bring health to your body and nourishment to your bones. (Proverbs 3:5-8)
We’ve all heard of the “placebo effect” – in a medical study, some patients are given medication, while others are given a placebo, a sugar pill without any medication in it.  Some of the patients who receive the placebo and believe that they are receiving medication recover from their illness, even though they have not received any medicine at all!  The only explanation doctors can offer for this recovery is that the mind and body are connected in very complex ways.  The mind, when it hopes for and believes in healing, can actually heal the body in some cases.  The opposite is also true: in the inverse of the placebo effect, sometimes called the nocebo effect, doctors have observed that people who think they will get sick often do, and that patients who do not think it is possible to recover from an illness often do not.  Sometimes, people who are receiving a placebo pill will even complain of side effects from it!  You’ve probably noticed another common way in which our attitude or state of mind has a lot to do with our health: people who are stressed out are more likely to get sick.  If you think back to some of the times when you’ve had the flu or when you had a cold that seemed impossible to get rid of, chances are it was during a time when you were under a lot of stress – usually, when you could least afford the time to be sick! 
Although it is only relatively recently that modern medicine has begun to explore the “placebo effect” and the effect our minds have on our bodies, the Bible has contained this wisdom for centuries.  (This should come as no surprise to us, since the God who inspired the Bible is the same one who created humans and therefore knows how we work!)  The book of Proverbs describes the connection between the mind or spirit and the body.  Proverbs 18:14 tells us that “A man’s spirit sustains him in sickness, but a crushed spirit who can bear?”  Proverbs also tells us that having a positive outlook on life – even a good sense of humor – can help us to be healthier in our mind, spirit, and body: “A cheerful heart is good medicine, but a crushed spirit dries up the bones” (Prov. 17:22).   
Christians and non-Christians alike may experience the placebo effect, or may increase their mental and physical well-being by maintaining a positive outlook on life.  Proverbs 15:30 is a general statement that can be true for anyone:  “A cheerful look brings joy to the heart, and good news gives health to the bones.”  But as Christians, we can have a sense of well-being that goes beyond this placebo effect because we have the ultimate “good news” of Jesus.  Of course, we know that in earthly life we cant expect to be free from all sickness or to be happy all the time, but we can possess that “peace of God, which transcends all understanding” (Phil. 4:7) even in the midst of serious illness or trying times. 
We pray: Thank you, God, for the amazing way you have designed our minds and bodies.  Help me to sustain a cheerful heart even when things just aren’t going my way – I know that my attitude toward life can help me feel a lot better, even when I’m sick.  Give me opportunities to share that all-surpassing peace with others by the way I handle the hardships in my life.  In Jesus’ name I ask all this, Amen.