Diana Nyad used just one word - "euphoric" - to describe how she felt upon reaching the shores of Key West Monday at the end of a 112-mile, record-breaking swim.

But it was three words that Nyad, 64, relied on over the past year, she revealed today on " Good Morning America," to conquer a feat - swimming from Cuba to Florida without a shark tank - that had previously eluded any other human being and Nyad herself in her four previous attempts.

What Makes Athletes Like Diana Nyad Strive?

"I decided this year to use a mantra … and the phrase I decided to use was 'Find a way,'" Nyad told "GMA" anchor Robin Roberts.

"If something is important to you and it looks impossible and you're up against it, just step back for a minute and say, 'Really? Do I have the resolve to think of everything [to the] nth degree to get through this?' and most times we do," she said. "People give up too quickly."

Nyad never gave up in this, her fifth attempt, at the swim, even when her face and body were lacerated from the saltwater and the custom-made mask she wore to protect herself from box jellyfish, a stinging jellyfish that had caused her to stop her last attempt because of burns left on her limbs and face.

In the final homestretch, Nyad, a Los Angeles native who made her first try at the record in 1978 at age 28, said she and her 35-member crew could see the lights of Key West ahead, which focused her mind and changed her thinking.

"I had 15 hours to think. Fifteen hours to stroke and think about this journey," Nyad said. "You know, so many people discuss the journey and the destination. Well, the destination was always my vision of the palm trees and the shore, but the journey, I didn't make it, for the last few years and that journey was thrilling. It really was. The discovery, the people, the looking inside of what you're made of but to finally get to the destination?"

"I tell you, I was euphoric yesterday," she said.

A competitive swimmer from early on, Nyad began striving for the Olympics as a young girl but was sidelined at 17 with endocarditis, a virus in her heart. She overcame that ailment and swam the 28 miles around the island of Manhattan in just under eight hours in 1975 and, four years later, swam the 102 miles from North Bimini, Bahamas, to Juno Beach, Fla., in 27.5 hours.

Nyad said she may have been a more physically capable swimmer in those days, in her youth, but that there was a reason she accomplished her goal of swimming from Cuba to Florida this year, at the age of 64.

"How many athletes do you know, John McEnroe is one for sure, who say that they wish they could have played at the world class level in their 50s and their 60s because the power of concentration and their perspective of what it all means and what you're capable of are infinitely higher at this age than when you're a young 20-something?" she said. "I really do believe that endurance grows and, also, we can never discount, in any sport, the mental."

When Nyad walked up onto Smathers Beach in Key West Monday afternoon surrounded by her supporters to chants of "Nyad, Nyad, Nyad," she, through her fatigue, told the crowd to "Never, ever give up."

Nyad's message quickly became the headline of her record-breaking swim, an occurrence she said happened because her feat wasn't really about the swimming at all.

"I didn't have much energy to talk for too long, but he first thing I said, I looked around, because those people weren't from the world of swimming," she said. "They don't care about the world record. It wasn't an athletic event. It was a moment of human spirit."