Nostalgia actually has a pretty wild history. The term was coined in 1688 by a Swiss medical student who was working on his dissertation. And at that time, what he'd noticed was there were these soldiers that were coming down from the Swiss Alps to fight wars in the plains of Europe who were feeling very anxious and distressed. And so he coined the term 'nostalgia' to represent this pain associated with people's longing for their homeland - and he saw it very much as a disease. If you fast forward to the present day, you would discover that nostalgia is actually considered a psychological resource. It's actually very helpful for our health and well-being. And what we discovered through careful experimentation using tools of modern behavioral science, is that it's actually not the case that nostalgia makes people miserable. It's when people are miserable that they turn to nostalgia and nostalgia doesn't reinforce that misery, it actually comforts them. And then even more recently, we've discovered that it actually motivates and mobilizes us to improve our lives, and to pursue the goals that are meaningful to us.