1. Nyad's huge life lesson: Just because someone says something is impossible, that doesn't mean it's true.
"You can do all the computations you want as to why this is impossible and this can't be done," she told ABC News. "But don't ever tell me what the parameters of the human spirit are. We have no idea how powerful our hearts and our souls are. We only know how limited our muscles are."
"There is a feeling of character that builds when you say, 'I'm not a quitter,' no matter how cold, no matter how tough, no matter how much pain," Nyad, 66, added. "Even the box jellyfish, my spirit is bigger than that. And there's a character that stays with you a long time deep under. And to me it's worth testing one's self ... Most people have that chutzpah in them. And they want to live it out. They don't want to sit at home quietly and lock the door. They want to be out living it out."
2. Nyad reveals she faced many challenges early on, including molestation as a child -- but she didn't let that hold her back from reaching huge success.
"I have felt pain and anger, deep anger ... as together and as happy and as privileged as I am, it's still an imprint," she explained. "I have to admit that even all these years later, all these wonderful experiences later, there's an injured little girl in there still."
3. Being stung by a box jellyfish is beyond painful -- it can be deadly.
4. Nyad relied on a playlist of 85 songs to power through long swims -- and it was all in her head.
5. Swimming may look like a solo sport, but it takes a team.
Before reaching the Key West shore during her triumphant 2013 swim, Nyad circled around her team, thanking the dozens who devoted their time and energy to helping her make it from Cuba to Florida.
"They all gave and they all believed and they -- not one of them got paid a dime. And I asked them all to come close in a semi-circle. And I cried, just wept," she recalled. "And I said, 'Look, I guess I'm gonna stumble up on that beach pretty soon. And I guess somebody's gonna take my picture. But don't you ever forget because I will never forget that we did this as a team. We made history together.'"
6. 60s are the new 20s for Diana Nyad.
"There's no doubt that I am in the prime of my life today. And you could say in some ways, well, of course we all say that, as we get older we mature. And we have better perspectives and we realize how precious every day is. There is all that. And that brings a wealth of new experience. But I actually think I'm physically better than in my 20s," Nyad said. "I don't get sick very often. My immune system is more resilient. I'm brute stronger ... I actually think just because of the mind and the emotional set of being mature, I am a better athlete in my 60s than I was in my 20s."
"The only bad dip in that entire two years (following the Cuba swim) was 'Dancing with the Stars' ... I am a rabid fan. I love it. I am not a bad dancer. As a matter of fact, some would say quite a fluent dancer," she said. "But, you know, people don't understand what a competition is. First of all, I have to get real. The first day we're there, Meryl Davis comes over. She can't help herself. She does a pirouette and an arabesque or something, tips her leg over and gets a piece of cantaloupe. And (my dance partner) Henry and I said, 'We are so screwed.'"
8. She wants a million people to walk across America with her.
"We've become a largely sedentary society. A doctor from Arizona State, his big new phrase is, 'Sitting is the new smoking.' And so next summer, my buddy, Bonnie, and I -- we're going to walk cross country. We're going to do it from L.A. to Washington D.C," Nyad said. "We want to get a million people out on the road with us and another million remote wherever they live -- Sydney, Australia, Bangor, Maine. And when we finish, we're going to say, 'You know what? Today is the day we made America a nation of walkers.'"
9. Her message and motivation right now.
"Life is short. It is fleeting," she said. "This life that we're living here on earth has an end, we're all on a one way street. Why not live it big? Why not live it with dreams and aspirations and be everything you can be? Tap every ounce of potential and courage that's in you."