Kindness begets kindness, according to science:

Goodness spurs goodness: A single act can influence dozens more.

In a game where selfishness made more sense than cooperation, acts of giving were “tripled over the course of the experiment by other subjects who are directly or indirectly influenced to contribute more,” wrote political scientist James Fowler of the University of California, San Diego, and medical sociologist Nicholas Christakis of Harvard University.

Their findings, published March 8 in the Proceedings of the National Academy of Sciences, are the latest in a series of studies the pair have conducted on the spread of behaviors through social networks.

In other papers, they’ve described the spread of obesity, loneliness, happiness and smoking. But there was no way to know whether those apparent behavioral contagions were actually just correlations. People who are overweight, for example, might simply tend to befriend other overweight people, or live in an area where high-fat, low-nutrient diets are the norm.

According to the the researchers, "the explanation lies not in calculations of odds and rewards, but in simple behavioral mimicry: Monkey see, monkey do, human style. When people are irrationally generous, others follow suit."

Nice.

Like yawning.

Better than yawning because compassion is good for your health.

Poor fitness, car purchases, lateness, having children, charitable contributions, divorce and stupidity are all contagious.

The quickest way to change yourself -- for better or worse -- is to change your context.

So there's good contagious (improve yourself!) and there's bad contagious (makes you sick!).

The key in life is to increase the good and decrease the bad.

Barker is spot on--environment rules.  And then so is Rifkin, increase the good...

We are each other's environment, as well as our own.

Yes, and we are also feedback loops that reinforce the behaviors we want to see in others.