Great post! If it is true that emotions are contagious, and my experience suggests that it is true, then we get what we give. If we get what we give, why not communicate and interact with others positively? Our lives and those who enter into it would mirror that back to us.
If you're interested in learning more about this phenomena, a good jumping off point would be looking into mirror neurons. Emotional contagion is another perspective I find compelling.
RE: Contagious Emotions - Confidence in yourself