Everyone experiences failure, says tennis legend Roger Federer. His advice for overcoming adversity: Let it go.

People who succeed "know they'll lose again and again, and have learned how to deal with it," Federer, 42, said in a commencement speech at Dartmouth College earlier this month. A video of his remarks, posted to YouTube by the school, has racked up more than 1.7 million views, as of Thursday afternoon.

Federer, who won 20 Grand Slam singles championships during his storied career, said his natural talent on the court only got him so far. He credited his career longevity and consistency, at least partially, to a staunch reliance on growing his mental resilience.

"When you're playing a point, it has to be the most important thing in the world," Federer said. "But when it's behind you, it's behind you. This mindset is really crucial, because it frees you to fully commit to the next point, and the next point after that, with intensity, clarity and focus."

"The truth is, whatever game you play in life, sometimes you're going to lose ... But negative energy is wasted energy," he added.

In Federer's case, he lost more frequently than a casual onlooker might suspect.

"In the 1,526 singles matches I played in my career, I won almost 80%," he said. "What percentage of points do you think I won in those matches? Only 54% ... When you lose every second point, on average, you learn not to dwell on every shot."

How to grow your mental resilience

Developing a short memory, especially when it comes to setbacks — as small as your friend being mad at you, or as large as losing your job — is highly valuable, experts say.

The more you fixate on difficult moments, the more you encourage self-criticism and a pessimistic inner monologue that prevents you from moving forward, according to Judy Ho, a neuropsychologist and professor at Pepperdine University.

"Sometimes we think that negative self-talk helps us to be motivated," Ho told CNBC Make It last month. "So, we beat ourselves up in our head thinking, 'Oh, this is going to motivate me.' But, actually, we just end up fulfilling a self-fulfilling prophecy."

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Letting go of painful or frustrating feelings doesn't necessarily mean suppressing your emotions, either. Allow yourself to experience your feelings and let them flow through you, Yale School of Management lecturer Emma Seppälä wrote for Make It in April.

"Let the emotions wash over you like a wave that comes, keeps you underwater for a bit, but eventually passes so you can resurface and take a breath of fresh air," Seppälä wrote. "Note that fully experiencing the emotion doesn't mean fully expressing it during its peak ... The point here is that by experiencing your emotion, you process and digest it. You'll communicate better once you've taken those steps."

Federer echoed that same advice: Take the time you need to recognize and process an upsetting situation before putting it behind you, he said.

"You accept it, cry it out if you need to, and then force a smile," Federer said. "You move on, be relentless, adapt and grow, work harder, work smarter."

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