Two words are standing between you and workplace success: "Thank you."

Psychologists Dr. John Gottman and Dr. Julie Schwartz Gottman, who studied 40,000 couples, found those simple words were the No. 1 phrase used in successful relationships. That advice applies just as much to the business world, too.

For starters, saying "thank you" is good for your health — no matter the context. Research shows expressing gratitude is consistently and closely linked to greater happiness, stronger relationships and an improved ability to cope with adversity. 

It's also one of the most crucial things a manager can do, according to former Insider editor-in-chief Jim Edwards, who went from managing a small team of journalists to hundreds of employees around the world over the course of his career.

In his 2022 book "Say Thank You for Everything: The Secrets of Being a Great Manager," Edwards outlines 19 things every new manager needs to learn — and saying "thank you" is the kicker.

"You can defuse virtually any job stress among staff by saying 'Thank you for doing that ... it was a lot of work and it did not go unnoticed,'" Edwards writes. 

Employees want to hear it: In a survey of 1,500 U.S. workers, 75% thought motivation and company morale would improve with a simple "thank you" from their managers.

But most weren't getting real-time gratitude. Two out of every three workers surveyed said their manager could improve at giving in-the-moment, positive feedback. 

The reason we like being thanked is because it makes us feel noticed and appreciated, the Gottmans note. Managers can start by saying "thank you" for small, everyday tasks. You're simply letting employees know you recognize and acknowledge their efforts.

Then, take it a step further: What do you see in their work that makes you value it so much? Explaining why you appreciate someone's work will make them feel even more seen. 

The business benefits of saying thanks

Saying "thank you" has other major business impacts beyond boosting employee morale. 

Companies that spend even 1% of their payroll on employee appreciation programs are more likely to retain employees and attract new candidates, found a 2016 survey from the Society for Human Resource Management and HR software company Globoforce (now known as Workhuman).

And "thank you" is a shockingly simple way to put someone at ease in a tense situation, like when an employee has a complaint about a coworker. To avoid sounding dismissive, it helps to lead with the two magic words, career experts Adaira Landry and Resa E. Lewiss wrote for CNBC Make It earlier this month.

Say: "Thank you for sharing this. Let's figure out a way to support you and address [X's] behavior." 

Even in the face of workplace conflict, those two simple words will take you a long way.

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