 However, in a recent article that was published in the Wall Street Journal, the director, Dr. Robert Wallinger, and associate director, Dr. Mark Schultz, pointed to the most significant contributing factor for physical health, mental health, and longevity, according to the data. Quote, close personal connections are significant enough that if we had to take all 85 years of the Harvard study and boil it down to a single principle for living, one life investment that is supported by similar findings across a variety of other studies, it would be this.