What does it actually mean to be a grown-up?
"Adult," for contrast, has a legal definition. In the US, a person suddenly gains all the powers and obligations of self-determination at the age of eighteen, like a switch has been flipped and they are no longer dumb teenagers who can barely be trusted to wash themselves. Maybe this is why "adulting" has become a verb. It's an act that we put on and take off when circumstances call for it.
It's a necessary façade of functioning that requires rigid maintenance in order to mask all the ways in which we struggle and stall out, and how much we just want to curl up in a ball in bed and wait for someone to take care of us. But being a grown-up is different. There is no age that can make you a grown-up. Some children are grown-ups from a young age, while many people—maybe most people—go their entire lives without ever growing up enough to even approach the concept. It's the easiest thing in the world to let life dissuade and distract you from the vital task of growing up. The constant flow of adulting tasks—which keep up the appearance of a serious person—become the consuming reality that saps our energy and attention, keeping us from the work of building real maturity.
An adult is someone who is legally recognized as having the ability and the obligation to understand the world around them in order to act appropriately and is generally expected to do the work of projecting that certainty. A grown-up is someone who sees that act for what it is and has the humility to realize that the world is far too complex for any one person to understand much.
The difference is particularly stark in the domain of rules. There's a nearly endless set of simple rules—set out in law books and etiquette guides—for how to properly adult. We are all force-fed a lot of these rules from childhood on: Always use the crosswalk. Dress for the job you want. Don't use drugs. Never discuss politics at a dinner party. But once you've learned enough of these rules to function, you can really stop trying—stop learning—and just coast along with that basic framework in place. A grown-up is someone who recognizes that there are very few real rules in life, but that they aren't so simple.
A grown-up is a person who knows that living well is a constant process of learning how to apply those few rules to new and changing contexts. If you don't have the patience or the humility to listen to others and to regularly question yourself and your conclusions about the world, you may make a great and successful adult, but you will never be a grown-up. Likewise, if you make the work of growing up the focus of your life, you are likely to fail by many of the metrics by which adults are measured.
Having watched myself and loved ones struggle with the work of growing up—or reject it outright—I have come up with a handful of rules that remain open for revision and amendment, but generally work well for myself. I have no ambition to be Jordan Peterson, but maybe you will find them useful too:
Never assume that life is fair for anyone, but don't give up on the idea that it should be fair for everyone.
Recognize that you are an animal—with animal drives and instincts that can disguise themselves as rational thoughts.
Accept that hurt and regret are inevitable, but let yourself be a little afraid of them anyway.
Find new ways to challenge yourself—with ideas, tasks, experiences—to avoid becoming complacent.
Don't assume that you "have things figured out," or that anyone else does either.
Seek out people you can be honest with, even when it's scary.
Recognize that every person knows some things that you don't—whether or not they'll ever share them.
Try to treat others the way you believe they want to be treated, until they give you a reason to treat them otherwise.
Don't place winning above kindness.
Recognize that you are not the center of anyone's focus but your own, even when they hurt you.
Try to take the drama of life in stride, but don't suppress your true feelings.
And lastly, know that these rules—and any others you might find—are incomplete and inadequate to the task of growing up. Make your own.