Yes, that sounds like a sales pitch...but it's not.  Happiness is good for our brains and good for handling stress better - in marriages, if you are feeling upbeat you are more likely to be able to take some bumps in the road.  If you're feeling down, pretty much everything seems grim.  Here's a link to a UTube TED talk on happiness that will not only make you laugh out loud, it also has a very important message about happiness.  I urge you to watch it...and also to try two exercises.