We usually think of forgiveness as something personal between the person who was hurt and the person who caused the hurt. But research done here in New Zealand suggests forgiveness may have effects that reach far beyond the individuals involved. In fact, forgiveness may even have the potential to be a powerful public health tool. Dr Richard Cowden is a psychologist and research scientist with the Human Flourishing Program at Harvard University. His work has consistently shown that holding onto resentment and unresolved hurt can take a real toll on both mental and physical health. Now in collaboration with researchers from Auckland and Victoria University, he's explored whether increasing forgiveness could have benefits on a larger scale.