(this excerpt came from an article by David Bulmer, 13 Rules of Leadership for Communication, Influence and Social Media Strategy)
Enthusiasm is contagious. David Zinn states that a positive can-do attitude increases the chances of success. We can never know how much we influence the people we lead. The effect of either our optimism or our pessimism can be enormous.
I have previously quoted Oprah Winfrey as saying that: “People don't change behavior or positions based on what they know. They change based on what they feel." This is an extremely powerful and clarifying statement. If you connect with people with a sense of optimism, purpose and a position of strength you will accelerate change that will carry and multiply through their [people] channels and relationships.
If someone gives off negative energy....ditch'em and move on.