But the struggle to become a person and to have a genuine relationship can hold people together, perhaps more effectively than a desire for happiness and unbroken togetherness. I’m not saying that a relationship should be painful but that the happiness sought for might be deep and complex, not superficial and simplistic. Therapists who aim at simple happiness for a couple in their care may either feel frustrated eventually or misguide the couple toward an ideal of superficial togetherness.

Instead, it is the quality of your relationships that matters. Simply put, living in the midst of warm relationships is protective of both mind and body.

This is an important concept, the concept of protection. Life is hard, and sometimes it comes at you in full attack mode. Warm, connected relationships protect against the slings and arrows of life and of getting old.

Once we had followed the people in the Harvard Study all the way into their 80s, we wanted to look back at them at midlife to see if we could predict who was going to grow into a happy, healthy octogenarian and who wasn’t.

The same is true for social fitness.

It’s not easy to take care of our relationships today, and in fact, we tend to think that once we establish friendships and intimate relationships, they will take care of themselves. But like muscles, neglected relationships atrophy. Our social life is a living system. And it needs exercise. You don’t have to examine scientific findings to recognize that relationships affect you physically. All you have to do is notice the invigoration you feel when you believe someone has really understood you during a good conversation, or notice the tension and distress after an argument, or the lack of sleep during a period of romantic strife.

Our basic relationship needs are not complicated. We need love, connection, and a feeling of belonging. But we now live in complicated social environments, so how we meet those needs is the challenge.

Focus first on what’s working well. This is the easiest place to begin. Take a look at the relationships on the energizing side of your social universe and consider how you might solidify or encourage what’s great about them. Tell (and show!) those people how much you appreciate them, and why. It never hurts to double down on what’s already bringing energy and vitality into your life. These relationships are already rolling, but there are usually one or two that have slowed down and need a little push to get up and running at full tilt again. Even good relationships tend to repeat the same routines over and over. It might be time to try some new things with them.