Shasta Nelson, relationship expert and author, says that work friendships are critical to individual and organizational success but acknowledges that it's not always easy to build these personal -- but still professional - connections, especially when work is virtual. She explains why consistency, vulnerability, and positivity are fundamental to friendship and offers specific suggestions for how to build those things with colleagues. Nelson is the author of the book "The Business of Friendship: Making the Most of Our Relationships Where We Spend Most of Our Time."