Nelson Dellis can memorize more than nine decks of cards — repeating each card in the order in which they were presented to him — in 30 minutes. In 15 minutes, he'll rattle off 201 names you mentioned to him only once.
Dellis, 33, is a four-time champion of the USA Memory competition, an annual event at which individuals attempt to memorize as much information as possible.
"When you have a good memory, you have better confidence in your memory," Dellis tells CNBC. "When you have that confidence, then you can focus your mental energy on other things, like being a good leader, boss, employee, speaker, influencer — whatever."
Boosting your memory and becoming more mentally sharp is easier than people think, Dellis says. A simple daily exercise that he recommends can dramatically improve your cognitive abilities, boost your confidence and help stave off memory loss.
Here's Dellis' trick for becoming more mentally sharp:
1. "Find a list of words 10 to 20 words and just sit there and try to memorize them," Dellis tells Lewis Howes on his podcast, "The School of Greatness."
These words can be random, such as names of presidents or authors, or a grocery list. For each word, think of a corresponding image.
2. "Find a place that you know, like your house," he says, "and take yourself there." That, he says, is your "memory palace."
3. In that memory palace, "place those images for those words on a route around your house." After you place those 10 to 20 images around your memory palace, try to recall the list.
Dellis started his journey to memory mastery after losing his grandmother to Alzheimer's Disease. According to the Alzheimer's Association, the number of people diagnosed with the disease has drastically increased in recent years, and it now affects some 5.5 million people.
Seeing how his grandmother suffered, Dellis wanted to avoid the disease himself. He vowed to exercise his brain, and soon became a memory champion. He has since made it his mission to educate others about being mentally fit.
"We all understand what it means to be physically healthy," he says. "We exercise, eat right, sleep right, etc. in order to improve our physical health. But we never consider our brain health. Using your memory and brain makes your brain...well, sharper and fitter."
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The above photo was used under Flickr Creative Commons license.
Correction: This article has been updated to correct the number of cards Dellis can memorize.