'Show me few of your friends and I will tell you what kind of a person is you are' is an old adage. The recent findings of scientists Nicholas Christakis of Harvard University and James Fowler of University of California reconfirms the underlying principles of this adage.
As habits and influences spread in closely knitted groups, most important of them are friendship groups, lifestyle outcomes like obesity, losing weight, happiness or otherwise spread in these groups. Though they are not contagious flu or viral diseases, many habits and their outcomes of lifestyles spread like flu. These scientists conclude social networks are bad as they spread flu type viruses so quickly. But at the same time they are very good if the happiness is to be distributed.
So be in social networks that generate good vibes to feel and spread happiness. Start spreading the infection of your smile.