This is the Ted talk by Psychiatrist Robert Waldinger, the director of the Harvard Study of Adult Development.

For 75 years, his team has tracked the lives of 724 men asking about their lives, such as quality of their marriages, job satisfaction, and social activities, and also monitored their physical health. There are three lessons that we get from his study. The first is that social connections are really good for us, and that loneliness kills.