"Is Happiness Catching?"

In today's Times Magazine-

A key to happiness, say researchers, is "daily exposure to many small moments of contagious happiness. When you frequently see other people smile — at home, in the street, at your local bar — your spirits are repeatedly affected by your mirroring of their emotional state. Of course, the danger of being highly connected to lots of people is that you’re at risk of encountering many people when they are in bad moods. But Christakis and Fowler say their findings show that the gamble of increased sociability pays off, for a surprising reason: Happiness is more contagious than unhappiness. According to their statistical analysis, each additional happy friend boosts your good cheer by 9 percent, while each additional unhappy friend drags you down by only 7 percent. So by this logic, adding more links to your network should — mathematically — add to your store of happiness."

And:

[Happy subjects] influenced one another’s health just by socializing. And the same was true of bad behaviors — clusters of friends appeared to “infect” each other with obesity, unhappiness and smoking. Staying healthy isn’t just a matter of your genes and your diet, it seems. Good health is also a product, in part, of your sheer proximity to other healthy people."

So: have lots of healthy and happy friends, and try to give as good as you get. Infect someone with a smile. The "up" multiplier is stronger than the "down," positive good vibrations are contagious.