This 5,000-year-old Korean secret to success and happiness can make you richer—here's how

While I was born in the United States and raised in an English-speaking household, some Korean words were impossible to escape.

One of the first words I learned as a child was "nunchi" (pronounced noon-chee), which literally translates as "eye-measure." The 5,000-year-old art of nunchi involves sensing what other people are thinking and feeling.

A person with "quick" nunchi can rapidly assess the overall mood and nature of relationships and hierarchies within any given social setting — and know how to respond appropriately.

In Korea, nunchi is a superpower. Not only is it the secret to living a happier life, but it can also help you perform better at your job, enjoy it more, keep it longer and continue getting the pay raises you deserve.

The wonderful thing about nunchi is that you don't have to be born with it. It can be honed by following a set of rules — such dropping your preconceptions (in order to observe your environment with discernment) and reading between the lines (because people don't always say what they're thinking out loud).

But there's one rule that's especially important if you want to make more money: Never miss a good opportunity to shut up. Why? Because if you wait long enough, most of your questions will be answered — without your having to say a word.

This may sound odd to many people, given that loudness is valorized in modern society, particularly in the West. I find this funny, since we also celebrate the stereotype of the "strong, silent" type, like cowboys or steely military leaders. But any skilled negotiator will tell you that being silent can put you in a highly advantageous position.

Take Thea, for example: Thea met with her boss to ask for a salary increase. She'd been offered a promotion already, but her new salary had not yet been decided.

An experienced negotiator might tell Thea to find out what range her boss has in mind before they start talking numbers. This follows the nunchi rule of never passing up a good opportunity to shut up; if you keep listening, the other party will tell you everything you need to know before you even ask.

Thea knew from previous observation that her boss has a tendency to get chatty and ramble. (If a room ever got too quiet, he'd often respond by filling it with sound of his own voice.) So Thea sat down with him and simply said, "I'd like to discuss a pay raise to accompany my recent promotion."

Then she left a silence that her boss felt obliged to fill. "I'm guessing you're cheesed off that we didn't give you the 3% increase last year," he said.

Thea was surprised; she wasn't aware she had been due a raise. Still, she didn't say anything. This of course made her boss talk even more. "OK, that's understandable," he said. "Two years' worth of salary increases would be a 6% bump, but beyond that? Hmm..."

Again, not a word from Thea. Her boss continued: "I mean, we can't pay you six figures. That's 25% higher than the highest-ranking member of your team."

And there it was! The answer Thea was looking for. Without realizing it, her boss had given her the exact range of what she should be requesting. Lower limit: a 6% increase on her current salary. Upper limit: $80,000 (a.k.a. Thea's estimated salary of the highest-ranking member of her team, based on the "six figures" — meaning $100,000 — that her boss blurted out.)

Thea knew the company would come with a lower but probably acceptable counteroffer, which they did. She ended up getting a 20% raise. And because her boss had shown his hand, Thea had the satisfaction of knowing she didn't shortchange herself.

It is said that a fair negotiation does not start until at least one party is offended by the other's offer. If your boss is shocked by your number, do not cower. It means you did the right thing.

Of course, this tactic won't fully work in every situation. Maybe you used nunchi to negotiate the price of a house you really liked. You used your eyes, ears, and a quiet mind to assess the environment. You maintained verbal minimalism.

And yet, you still had to walk away because the owner was inflexible about the price. That's not your fault. It's still a small victory, because your agent now knows that you're not easily impressed.

Since you established an image of stoicism from the very beginning, you're now in a much stronger position for all the future houses your agent will show you. You have nothing to lose (or, at the worst case, very little).

So take charge of your nunchi and be the strong, silent type. The loudest person in a negotiation isn't always the winner. Leave silence and space to allow people to come to you.

Euny Hong is a journalist and author of "The Power of Nunchi: The Korean Secret to Happiness and Success." Her work has appeared in The New York Times, The Financial Times, The Washington Post, The Wall Street Journal and The Boston Globe. Euny graduated from Yale University with a B.A. in philosophy and is a former Fulbright Scholar.

Don't miss:

• This 30-year Harvard study found the 5 simple habits that may prolong your life by a decade or more
• Billionaire Jeff Bezos: To live a happy life with no regrets by age 80, ask yourself these 12 questions
• Stanford psychology expert: This is the No. 1 skill parents need to teach their kids—but most don't

Like this story? Subscribe to CNBC Make It on YouTube!