​Proverbs: 17:22 "A cheerful heart is good medicine..." (on, Why should I be happy?)
https://www.hsph.harvard.edu/news/magazine/happiness-stress-heart-disease/
http://greatergood.berkeley.edu/article/item/six_ways_happiness_is_good_for_your_health
http://www.dummies.com/relationships/happiness/the-benefits-of-happiness-and-positive-emotions/
http://www.happify.com/hd/whats-so-great-about-happiness/
http://happyproject.in/message/advantage-happy/
​https://www.theguardian.com/lifeandstyle/2014/nov/03/why-does-happiness-matter
​http://thehappinessshow.com/HappinessBenefits.htm#benefits list

What does it mean to be happy? What is happiness? (How does happiness feel? How do you know when you feel happy?). That question might not be so easy to answer. Happiness is hard to define. But one thing for sure, we know it when we feel it.
​Matthieu Ricard: “Happiness is a deep sense of flourishing, not a mere pleasurable feeling or fleeting emotion but an optimal state of being.”
http://apa.org/pubs/journals/releases/bul-1316803.pdf  (53 page study on positive effects of happiness)
http://www.mindbodygreen.com/0-21493/16-ways-exercise-makes-you-happier-infographic.html
http://www.mindbodygreen.com/0-14340/why-sex-is-good-for-your-health-infographic.html