Ahh, the pursuit of happiness. So many voices in the chorus telling us how to master it. There are psychology-based tricks to happiness, watch-outs for what kills happiness, even equations for happiness.

Despite all the sources of inspiration on the topic, it’s hard not to take notice of an authoritative, 81-year-long study conducted by the big brains at Harvard University. Known as the Harvard Study of Adult Development, it is one of the most comprehensive longitudinal studies in history.

Started in 1938, the Harvard study has been seeking to answer one question: What keeps us happiest as we go through life? The research started by tracking the lives of 724 men. Any original study participants left are now in their 90s, so now the study is examining the lives of 2,000 children of these men. This just might go on longer than The Simpsons.

As psychiatrist Robert Waldinger, the study’s fourth director, said in a recent TED Talk, the core conclusion of the study is breathtakingly simple: “The clearest message is this: good relationships keep us happier and healthier. Period.”

Life is relationships.

The study also elaborates on the happy and healthy part. First, an unexpected health benefit of maintaining relationships throughout one’s life; it protects the brain and preserves memory longer. Knowing you have people you can count on when things get tough keeps the brain healthy and less anxiety-ridden, thus sharper.

And having social connections means you live a longer, happier life — but loneliness kills. People who are more isolated experience health declines sooner (including declines in brain functioning), are far less happy, and die sooner.

Waldinger points out that you can be lonely in a crowd or a marriage, so it’s also about the quality of relationships, not just the quantity.

But if maintaining relationships was easy, everyone would do it.

Here are some common things that get in the way of forging and fueling relationships, and how to overcome them.

The work of it never ends.

Relationships can be exhausting, but they have to be a priority. Period. Doubling down on the investment you make in those that matter to you will matter in the end. And as for those friends who do fade for whatever reason, it’s critical to keep plugging in new ones. Waldinger says, “Those happiest in retirement were people who’d actively worked to replace workmates with new playmates.”

Having left the corporate world for the life of an entrepreneur (where I’m no longer surrounded daily by friends), I can tell you that keeping up with friendships is some of my most important work now.

That thing not said.

My wife and I base the strength of our marriage on our communication. Nothing gets left unsaid. I have seen friendships, marriages, and all walks of relationships rot from the inside because of a lack of courage in communicating the hard things.

The hard things are hard. The easy things are easy. The former strengthens bonds, even if it doesn’t feel like it at the time. To overcome the fear of saying that hard thing, try this simple trick: think of it as a bee sting. It will hurt at the moment it’s happening. But it’s soothed immediately thereafter if you apply salve, in the form of empathy and deep listening. And then everyone can move on.

Family feuds.

Grudges do no one any good. Look in the dictionary under “Life’s too short” and you’ll find this. My dad was world-class at starting mystery fights with extended family members and holding grudges (and my mom even better at cleaning up behind him to keep the peace). It cost us a fair amount of potential family connectivity/joy.

Family-conflict expert Dr. Phil says the key to resolving family fights is to first recognize the impact the feud is having on the rest of the family, and then step up with a choice to forgive. Then get clear on what the disagreement is really about (sifting through emotions), seek to understand the others’ point of view, and extend an olive branch.

Work is only getting more intrusive.

Work-life integration has replaced work-life balance. We’ve never had more access to more distractions, devices, or demands. Integrating work into your life doesn’t mean it becomes your life. The integration part also means integrating with those you care about.

Strengthening relationships in the face of ever-increasing work demands involves redefining what success really is for you. In the end it’s a choice. I wish I had a more clever solve for you, but it really boils down to that. If success starts and ends with nurturing relationships, then everything else gets re-prioritized. You’ll find the things that go by the wayside to make room for relationships will soon seem trivial in comparison.

These researchers have been studying how to be happy for 81 years. Let’s learn from history to create a happier life, and one we can remember more clearly.