Watch: The Greatest, Proven Life Lesson You’ll Ever Receive

As the world slowly turns its head toward the importance of personal happiness, we’re becoming increasingly aware that the key to a satisfying life lies not in the celebrity’s spotlight or a million dollar paycheck but in something far easier to attain. There is a currency more valuable than anything else in the life of a human that will yield not only good emotional wellbeing but physical health too, and it’s something that we’ve always had access to: personal relationships. Good personal relationships, to be specific.

Watching this insightful 12 minute video, in which psychiatrist Robert Waldinger discusses the finding of the longest ever study on human development (75 years and counting), you’ll find it a whole lot easier to let go of a toxic friendship that’s been getting you down, or leave the marriage that exists in permanent conflict.

Over 75 years, Waldinger and his predecessors have studied the entire lifespan of roughly 60 men (they started out with over 700, but it’s rare that a study like this would continue beyond a decade), tracking them from their childhood and teenage years right through to the present, when those 60 remaining men are in their 80s and 90s. So what was it that made the ones that were healthy and happy, healthy and happy? Was it fame? Was it money? Promotions at work? And of those who didn’t grow up to fair as well, what went wrong?

As Waldinger explains, we’re told to ‘lean in’ to our careers and lean into opportunities for success when, as this study plainly shows, the one area of our lives we should be leaning into are our relationships. Those who enjoyed healthy relationships were both happier and physically healthier as a result. Those who remained in relationships that were fraught with difficulty actually saw their health suffer more than those who went through a divorce. Looking back, those who were in satisfying healthy relationships in their 50s were the healthiest among the group of participants when they reached their 80s.

Those in relationships that made them feel protected, where you could count on your partner, enjoyed better mental and physical health while those whose relationships could not be relied upon suffered from memory loss and a decline in brain function. Of course, those who were in successful relationships still experienced the odd squabble, but these inconsequential arguments took no notable toll on the health of those involved. Of all the people involved, it became clear, after a hell of a long time, that those who leaned into their relationships fared far better than those who worked 70 hour weeks, leaning into their careers.

Robert’s parting advice? Make an effort to replace screen time with people time, go out of your way to put family feuds to rest. For those who are retired, make an effort to place former workmates with playmates. Those who actively invested in their relationships were the happiest and healthiest, and that’s it.

So, you’ve been fighting daily with your boyfriend, you can’t seem to make it work, and your emotional wellbeing is waning? Cast your eye ahead to life in your 50s, 60s and 70s; will this relationship be a good thing that contributes towards a happy life or is it standing in the way of the relationships that will serve you best?