The Finns have a word specific to the tenacity and perseverance people display when they endure in the face of seemingly impossible odds: Sisu. Emilia Lahti, a positive psychology expert and researcher, is the face of sisu to the world outside Finland. Using articles, a TedX talk, social media, and events to promote sisu, she is passionately working to help us all understand what sisu is, why it's important, and how people might develop it.