There are lots of bits of advice you probably weren’t given growing up. How to budget your money. How to know if you should marry the person you’re dating. How to make or break a habit.

Also assuredly on that list: How to make friends in adulthood.

Not only is it not part of any school curriculum, but you probably didn’t receive any guidance from your parents, either verbally or by way of example, as there’s a good chance they didn’t have any real friends themselves.

If, as a result, you’re struggling to find pals as a grown-up, here are three lessons on the subject, found through our own process of trial and error. Better late than never. Hopefully they’ll keep you from groping about quite as blindly.

You’ll Have to Be Proactive

You likely never even gave any thought to the idea of making friends in general until you graduated from college and plopped out into the wider world. Why would you have? Making and having friends during your school years is practically as natural as breathing. You’re interacting with peers, probably of similar backgrounds and ages, for six or more hours a day. You further subsect this peer group into segments of the even more like-minded by sorting into various extracurricular activities. It’s hard not to make friends during your school years.

And then, post college, cue that record scratch. You may see fellow humans at your workplace, but the pool of potential candidates in the friend department — folks who are in a similar stage in life, share your interests, and possess a personality with which you connect — may nevertheless be rather shallow. And if you work from home, as more and more people do, you can go days without seeing other human beings, of any stripe, at all.

In adulthood there are few built-in structures that automatically push you into forming friendships. And most freshly-minted grown-ups, who have little experience in environments that aren’t set up with those structures, try to continue the friendship-making method they’ve always employed — which is to say, doing nothing — and then feel befuddled at their anemic social circle.

So the biggest lesson to learn about making friends in adulthood is that it’s going to take real, proactive effort. It won’t just happen; you’ll have to work to make it happen.

That means intentionally increasing your contact with other humans, i.e., possible future friends. That can be accomplished by attending a church, joining a gym or dojo, finding a meet-up group in your area that centers on some interest of yours, etc.

Being proactive also means deepening the more superficial bonds you’ll form in such situations by inviting someone to hang out outside of them. For example, if you find yourself chatting each Sunday with someone at your church, eventually you invite them over for dinner. (For tips on how to make these invitations in a non-awkward way, read this article.)

One of the best ways to turn acquaintances into real friends is to start some kind of group — whether that’s an informal men’s fraternity or a discussion circle like a book club — that meets weekly/monthly. With starting a group, you invest more effort upfront to get it going, but then have to put in less effort later in sustaining it; having a set day/time that you meet with your friends will help “automate” your relationships and prevent the endless back and forth of deciding on a time to hang out, every time you hang out.

It Will Take Time (A Lot More Than You Think)

A research study surveyed both college students and adults to figure out how much time it takes to make friends and deepen these bonds.

It found that turning an acquaintance into a casual friend requires students to spend about 40 hours together and adults to spend about 90 hours together.

Turning a casual friend into a regular friend took about 60 hours for students and 160 for adults.

And turning a regular friend into a good, close friend took about 120 hours for students, and 100 for adults.

All in all, it takes college students about 220 hours of together-time to move through the stages/levels of friendship from acquaintance to best friend, while it takes adults 350.

Adults thus have two big disadvantages in the friendship-making department: 1) It takes more sheer hours to progress a relationship than it did when you were young (the researcher who