Here’s something we can all do to improve health: smile.  Trained as a scientist I am not one to make wild claims (longer life!  less illness!  fewer strokes and heart attacks!!) without backing them up–so here are some studies and citations.  Several of the links are to easy-to-read articles that distil the meaning of one or more studies; if you like to take things all the way back to the source, you’ll find their references at the end of those articles!

Smiling Makes You Happier

Happiness Results in Better Immunity

Positive Attitudes Reduce Heart Disease

Smiling Reduces Experience of Pain and Anger

So, put a smile on your face!  It’s good for your health.