What's the quickest way to ruin a friendship? Do great friendships have anything in common? Are close friendships in the workplace such a bad thing? These are just a few of the questions that bestselling author Tom Rath asked when he embarked on a massive study about the impact of friendships. His team's findings— including the landmark discovery that people who have a "best friend at work" are seven times as likely to be engaged in their job—are sure to challenge long-held assumptions peo...