You fetch your mail, and there among all the bills and credit card applications is a card-sized, hand-addressed envelope. (Question #1: Who in the world still sends personal notes? Question #2: Why don’t we all do this…all the time?)

You’re puzzled. You don’t recognize the handwriting. It’s not your birthday. You open the envelope anticipating a thank-you for some wedding present or baby gift. Only that’s not what it is.

It’s a few lines from a girl who used to live three doors down. She’s starting her pediatric residency next month! And she’s thanking you for the huge part you played in her life more than a decade ago.

“Do you remember that afternoon?” she writes. “It was my first day of high school. You must have realized I was freaking out. You invited me into your kitchen and started baking chocolate chip cookies. When I began whining about how ‘impossible’ my classes were going to be, I remember you spinning around, spatula in hand. You wore a stunned look on your face. And what you said, in a shocked voice, was, ‘You are worried about grades? That’s silly! You’re the smartest kid I know. And probably the sweetest too—but you can’t tell my girls I said that!’ Then, like it was already a done deal, you said, ‘You’re going to end up in med school one day.’”

The note concludes, “You will never understand what you did for my heart in those moments. My home life—as you know—was beyond dysfunctional. So hearing you say you believed in me gave me a confidence I’d never had before. There’s no way I would be where I am, if not for you. I am forever grateful.”

Isn’t it strange that you can’t remember this incident, and she has never forgotten it? When a ninth grade neighbor was floundering in self-doubt, you tossed her a verbal lifeline—plus a lantern and a compass! How could you have known it would be your words she’d cling to all these years?

Here’s a recommendation: Take that priceless note and put it in a shoebox. It’s holy.

Keep the box somewhere safe. Then add to it. That scrawled message you’re going to find under your windshield wiper in a few weeks—the one from the grateful mom of the kid you’ve been coaching—stick that in your box too. Put it in there with the funny card of appreciation from the small group you lead. Slowly fill your box with every uplifting or affirming note that comes your way. Why? Because at some point over the next few years (maybe the next few months), you’ll likely find yourself wondering if your life has mattered. Or you’ll be trying to fend off those incessant voices that insist God could never (and would never) use anyone like you.

In a discouraging world, who among us wouldn’t be helped by a box full of encouragement like that?

Encourage is one of the best words we’ve got. It comes from an Old French verb meaning “to put heart or courage into someone.” In the New Testament the Greek word that gets translated encouragement conveys the idea of consolation, comfort, or challenge.

There’s one guy in the Bible who was so good at coming alongside others and cheering them on, everybody started calling him “Barnabas.” That nickname literally means “Son of Encouragement.” (In other words, if encouragement were a person and had a baby, it would have been this guy.)

There’s an idea for you: Name your collection of notes after this world-class encourager. Call it your “Barnabas Box. “

The point isn’t to create some kind of monument to yourself. (Though perusing your box from time to time is a great reminder that you do have it within you to influence others in good ways.) No, the idea is to let your box challenge you to cultivate an ongoing lifestyle of encouragement.

One practical way to do that is to give other people in your life regular “mailbox moments.” Can you imagine the impact if you took just ten minutes a week to sit down and write one short, heartfelt note of appreciation?

When we encourage others, it’s impossible not to feel encouraged ourselves. That’s certainly not the main reason we do it, but as perks go, it’s a pretty good one.