Happiness and freedom begin with a clear understanding of one principle. Some things are within your control. And some things are not.

Epictetus, Discourses

If we accept the wisdom—and more recently the scientific evidence—that our relationships really are among our most valuable tools for sustaining health and happiness, then choosing to invest time and energy in them becomes vitally important. And an investment in our social fitness isn’t only an investment in our lives as they are now. It is an investment that will affect everything about how we live in the future.

She was honest with him about how much this concerned her, and Joseph was well aware of her concern, telling the Study on several occasions that Olivia often told him how difficult he was to truly know. “I’m self-sufficient,” he said. “My biggest weakness is not leaning on anybody. I’m just made that way.” Joseph was tuned in enough to other people that he could see and articulate their difficulty with him, but he could never get past a core, deeply rooted fear that is not uncommon: he didn’t want to be a burden, or to feel anything but fully independent. Though he attended Harvard, Joseph came from humble beginnings, and told the Study that he learned the value of self-sufficiency as a child on his family farm, where he spent days on end operating a horse-drawn plow alone.

The complex emotional lattice of every family is unique in important ways, and our families affect us in ways that other relationships do not. Families share history, experience, and blood as no other relationships can. We can’t replace a person we’ve known for our entire lives. More importantly, we can’t replace a person who’s known us for our entire lives. Nurturing and enriching these relationships despite challenges, persevering, and appreciating the positive things we get from them is worth the trouble. Bob thinks of a moment when, as a young man, he was going through a time in which he was incredibly angry at his parents, and an uncle took him aside. I know you’re mad, his uncle said. But just remember: nobody is ever going to care about you this much ever again.

Thousands of stories from the Harvard Study show us that the good life is not found by providing ourselves with leisure and ease. Rather, it arises from the act of facing inevitable challenges, and from fully inhabiting the moments of our lives. It appears, quietly, as we learn how to love and how to open ourselves to being loved, as we grow from our experiences, and as we stand in solidarity with others through the inevitable string of joys and adversities in every human life.