One of the great joys of my life is that I get to spend time with some of the world's foremost experts and builders and call it work. I've recently decided that I'd like to try to record and share the insights from some of these natural conversations so that everyone can benefit from them in the way that I have.

Dr. Robert Waldinger is the director of the Harvard Study of Adult Development, which is the longest-running study on adult life, health, and happiness in the world.

5 lessons from our conversation: (1) Relationship satisfaction impacts health, (2) Loneliness kills (and it's more prevalent than ever), (3) Make social fitness a priority, (4) Check your energy to improve your life, and (5) Ambivalent relationships are the most toxic.