In less than a month, I'll enter my twenties and start thinking about big, future-y things (like what Netflix series I should start after I finish "House of Cards"). And while the start of your 20s is a time of thinking-you-have-your-shiz-together-but-failing, the end of your teens is kind of like being handed a pop quiz: Let's see what you've learned so far. This stuff'll only get harder. So here's what I've learned so far:

Find friends that are infinitely cooler than you. Love them hard.

Know that those same friends won't, and shouldn't, always be your encouragers. Plenty of people will tell you, "You can do this!" The people that matter will say, "You don't have to do this," or, "You don't want to do this," or, "You really, truly, actually cannot do this." Listen to them.

Read books. Don't be that person who can't remember the last time they opened a book. Read them all the way to the end. Then read more books — funny ones, heartbreaking ones, inspiring ones, boring ones, classic ones, short ones, long ones, beautiful ones. When you find one that hits you like a train, reread it.

Write, too — poems no one will ever see and letters you will never send and thoughts that take up too much space in your brain. You're allowed to write about the people in your life. (The good ones will have nothing to worry about, but you are under no obligation to write warmly about the bad ones.)

And the bad ones really don't matter. Stop explaining yourself to them. Do what works for you. Irrelevant people will make backhanded comments about you or your dreams or your talents as if they know better than you. Do they? Why do you need to justify yourself? You do you, buddy.

Grudges aren't worth it. They are never the hills upon which you should pick your battles.

Be passionate about anything (except for, like, heroin). Find something you like and let it be your thing. Be brave enough to let that thing define you, just a little. It's okay to be "the writer" or "the painter" or "the musician" or "the helper" or "the do-er" or "the thinker." Labels aren't all bad. They're just proof everyone else recognizes what we love or what we're good at.

By the same token, if you don't have a thing but have always wanted to have a thing, go find a thing. Learn it, study it, practice it. Be the boss of that thing.

No, you can't say hi to every dog in the world. But you can damn well try. 👊🏼

Know that most everyone is doing their best. The cashier who is ringing you up too slowly or the person who messed up your coffee order or the driver who accidentally cut you off are all trying their hardest. Maybe today's been rough for them. Maybe you should simmer.

Don't listen to people who tell you to "smile more." They are not the boss of your face.

Know what you stand for, even if it's not a stance that is definitively one way or the other. Not everything is black and white. But moral and theological and political convictions are literally the foundation of our world view. So make sure your convictions are sturdy.

Middle school is everyone's "we-don't-talk-about-that-anymore" phase. Get rid of any photo evidence those three years happened and move on.

It's okay to not be okay. Quietly confronting your problems alone is overrated. Share the ick; ask for help; vent; rant; allow others to hoist some of the burden onto their own shoulders. Feigned bravery isn't bravery at all.

Treat'cha self. Pay $1.00 extra for guac. Order fries instead of a side salad. Stop worrying about how flat (or how very un-flat) your stomach is. There is nothing more destructive -- yet entirely unproductive -- than wishing you were thinner or taller or prettier or [insert any adjective here]-er. Stop. Doing. That.

Comparison will kill you. Comparison will kill you. Comparisonwillkillyou.

Some apologies are half-assed. Learn to accept them even if they're less than what you were hoping for. And learn to accept the apologies that aren't given at all.

Say I love you sincerely and often. (Even though it's cliche; even though it's a threadbare phrase.) Say it when you're leaving and say it when you miss someone and say it when you need someone to know how good and rare they are. Say it to all the wrong people so you understand why saying it to the right people is important.

Try laughing with someone and not becoming their friend. I dare you.