Perhaps it comes as no surprise to find that healthier people are happier than those who aren't as healthy. In fact, a 2006 report published by the Pew Research Center found that 48 percent of people who rated their health as "excellent" described themselves as "very happy", while only 15 percent of those who rated their health as "poor" said the same.

　　After all, it's harder to be happy when living with chronic pain or illness or when faced with a potentially life-threatening condition.While health is strongly tied to happiness, lack of health is even more strongly correlated with lack of happiness. Of those who rated their health as "poor," a whopping 55 percent described themselves as "not too happy," while only 6 percent of those in "excellent" health said the same.

　　According to the Pew Research Center, health—along with religion and marriage—were among the strongest predictors of happiness, even when adjusting for a variety of other variables.