This is from Psychiatrist Dr. Cliff Khun, "America's Laugh Doctor":
Always Go the Extra Smile. This Commandment is doubly helpfully for depression and anxiety because not only does it provide measurable emotional and physical relief, but it also is completely under your control - regardless of your circumstances. Because smiling remains totally under your control, it can be your greatest resource for using humor's natural medicine to accelerate your mental health.
Smiling produces measurable physical benefits you can experience immediately: your stress decreases, your immunity improves, your pain and frustration tolerances increase, and your creativity soars. And guess what? You experience all these benefits even if your smile is "fake." That's right...forcing a smile onto your face perks up your immune system and lightens your mood just as readily as a genuine smile. Fake a smile and you'll soon feel well enough to wear a real one!
This is great news for your proactive stance on sustainable mental health. You have an amazing amount of pre-emptive control over your mood - you can, literally, choose more energy and happiness. The key for your use of this Fun Commandment in enhancing your mental health is to start practicing right now, so that smiling becomes an entrenched, habitual method of accessing the natural medicine of humor. If you wait to smile until your mental health has taken a turn for the worse, and depression or anxiety has taken hold of you, it will not be as effective.
In 1915, a song came out of England called, "Pick Up Your Troubles in Your Old Kit-Bag and Smile, Smile, Smile". Vide Press called it a "Philosophy Song". Do you think that attitude matters in warfare? I do. Do you think David was depressed or upbeat when he faced off with Goliath?