Want lasting happiness? Invest in your connections to other people, suggest Robert Waldinger MD and Marc Schulz PhD, codirectors of the longest-running scientific study on well-being. Here, they share four strategies to re-energize your bonds.

Why do humans often want to create a world of “us” vs. “them”? And what can we do about this unhelpful, often damaging, yet somehow reassuring instinct? Psychologist Robert Waldinger has some useful advice.