Judging by Instagram, the definition of a life changing experience is “quit your job and travel the world.” But for a trip to be truly transformative, it just needs to affect you in a way that lasts longer than your unintended sunburn.

You can have a transformative experience in as short as a long weekend, which actually happens to be the preferred length of a trip for millennial travelers, according to a 2018 report by Expedia.

That’s because these days, a vacation is about more than booking it to the beach for piña coladas on repeat. Today, travelers are more likely to prioritize spending on experiences over anything else, Expedia found. And nearly 70 percent want to do something interactive, a report published by PGAV Destinations called Meet the Millennials found.

A life changing experience is all about action and adventure: In 2018, 67 percent more travelers chose to book an outdoor activity like glacier hiking, bungee jumping, scuba diving, or mountain biking than the year before, according to TripAdvisor. And while more and more people are willing to take on those adventures solo, in an interesting twist, unusual experiences—say, an ultra marathon or cliff diving in the Philippines—tend to alienate people from their peers, research published in the journal Psychological Science revealed.

That’s where an obstacle race like Spartan comes in. Any race can push your physical and mental limits. But in an OCR, where obstacles can range from wall climbs to barbed wire crawls and fire jumps, the struggle is real. And those people alongside you? They may be your competitors, but they’re also your support network—they’re the only people who know exactly what you’re going through at that moment.

In fact, close to 80 percent of Spartan’s 5 million racers in the U.S. sign up as part of a team. And that shared pain can actually make you stronger as a group, another study published in Psychological Science found—essentially, it helps you bond. Even if you’re there on your own, undergoing a life changing experience with another person (even a stronger) can intensify that event, research shows.

Whether its an OCR or something like hiking Machu Picchu or shark diving in Bora Bora, it’s almost always better with friends. When people are paired up, they enjoy an experience way more than when they do it alone, according to a study from The Association for Psychological Science. People are also more emotionally responsive to experiences when their friends are going through the same thing, a study published in the journal SCAN found. And the pleasure from doing something awesome on your own is dwarfed by sharing that experience with someone else, according to one Harvard study.

The science is clear: Not only will doing tough experiences together strengthen your friendship, having your friend by your side will make you enjoy that experience even more. It’s a win-win.