We're pretty conditioned now to do everything with immediacy. Sending a thank-you note is no exception--experts now even recommend post-interview thank-you notes get to recipients within 24 hours, for instance. But as Leah Fessler summarizes in her article for Quartz, you shouldn't underestimate the power of a thank-you note written months or even years later.

Confirmation of meaning is precious.

Fessler cites author and organizational psychologist Adam Grant, who asserts that it's often difficult to see what the influence of someone's help is in the moment. You might have to wait a significant period of time before all the puzzle pieces fall into place and you understand just how massive their contribution to you was.

Now, you might be thinking to yourself, What does it matter? It's great the light bulb has gone off, but what are they going to care? Surely they've gone on to more impressive things, maybe even forgotten you by now, right?

Grant asserts that messages of gratitude, even when received long after the fact, can help others feel like the time they spent with you mattered. In essence, it confirms that, in some small way, they made a difference, that what they did had purpose and was worthwhile. It is this sense of purpose and meaning that ultimately leads to joy and satisfaction with life.

As psychiatrist Viktor Frankl put it in his1946 bestseller, Man's Search for Meaning, "[It] is a characteristic of American culture that, again and again, one is commanded and ordered to 'be happy'. But happiness cannot be pursued; it must ensue. One must have a reason to 'be happy.'"

So consider this in the context of a few statistics and facts:

In sum, just about everyone wants to feel like they've contributed. It's one of the most basic needs we have as living, social creatures. When we have that feeling, we do better, both in health and wealth. But quite frankly, our systems and culture don't make it easy to have that self-perception. In our "toss-away" society, where items are practically outdated before they're even released, it's easier than ever before to feel like we're irrelevant, like everything we worked for will fade as easily as dust blows away in the breezy heat. And in this circumstance, believing that someone else doesn't need to hear that they helped is one of the most sadly dangerous assumptions you ever can make.

Still hesitating? Don't. 

I know, I know. It can be a little awkward to reach out with something so heartfelt. But that's only because, in the back of our minds, we're afraid that the best response we'll get is a "meh." We worry that if we go out on a limb we won't get reciprocation, and that then we'll feel like we don't matter. There is perhaps nothing quite so painful as realizing that someone who means worlds to you doesn't reciprocally see the same value in you.

But oh, young padawan, this understand you must: The person who made a difference in your life made a difference because they saw your value long before you did. And the odds are good that, even after all this time and distance, they still see it.

So think for a moment. Who is it who has built you up? How did they change your life? Don't hesitate. It's OK to send them a note. In fact, they need you to.