of all the animals on the planet, we're the only ones who race each other for one. we try to conquer each other. we run, we climb, we swim competitive, and we've employed new and old ways to go faster -- horses, bikes, skateboards, skis. but what motivates us to compete, to drive our bodies to their limits? is it the desire to be best? the to break down barriers? >> no one has ever done a full

ironman. >> reporter: or just the feeling of reaching the finish line that keeps us going? we're about to take you around the world an extraordinary people competing in eight extraordinary races. they'll teach us why we push our minds and bodies and what we gain by doing this. >> the human spirit is a challenge. >> this is "fit nation: around the world in eight races." hello, i'm dr. sanjay gupta. over the next half hour we're going to go on a journey to discover the drive and motivation behind the human competitive spirit. what better place to start than at the beginning with one of the earliest types of competition -- running. as long as we've existed, humans have been running. our early ancestors didn't run for the joy of it. they ran for survival, two outrun and catch their prey. while most animals can run faster than us, humans are built with a unique advantage -- endurance. we can run longer distances and keep going after other animals have to stop.

that stamina gets put to the test every year in the country of wales. humans race against horses. man versus horse, a huge competition in a tiny welsh town. over 600 runners battle 22 miles of steep and slippery terrain trying to make it to the finish before 60 horses and their riders. >> would like to win. to tell your grandkids that you beat a horse is very cool. >> reporter: but to get here, tom fairbrother faced a far more serious challenge. a battle with bulimia. >> it's like these young girls, i think i wanted top show that a guy in his 20s, was athletic, was equally at risk. >> he started a campaign to raise money and awareness by running ten marathons in less than a year. he has one to go. man versus horse. >> the first horse that came past, i'd never seen or anything like it. you could feel the ground and

hear it coming. it seemed like fating way to end something that had been like a great journey -- >> third runner today, tom fairbrother! [ applause ] >> i'm really proud. doing this is hopefully showing people that you can recover and be stronger than you were before. >> will to fairbrother put human endures to the test racing against and even beating some of the horses to the finish line. sometimes our drive to compete isn't just coming in first. it's about proving to ourselves and others that we've got what it takes. our next racer did just that. powering past the naysayers with his own personal mantra. be the hammer. >> this race is probably the biggest thing that i've ever prepared for. all my other racing has kind of been in preparation for this. >> john young is training for his first ironman triathlon.

>> being a little prngs we grow up a lot with people telling us you can't do that, you're too small. we can't do that, you're too short. i want to show that any other person who's short statured, if they want to do something battle enough, they can prepare and do it. the ironman is a 2 p.4-mile ope swim, bike ride followed by a full marathon, 26.2 miles of running. no one with dwarfism has ever done a full ironman. i will be the first. >> it's been wonderful to watch him keep going and moving. >> it's been a big motivation for me. showed me that even dwarfs can do many things that average-sized people can. >> when i did the boston 2014 marathon and wasn't able to finish due to illness, i was upset. he said, sometimes you're the hammer, and sometimes you're the nail. that day i was the nail. now it's my chance to be the hammer. >> paddle, brother! >> crossing that finish line is

going to be probably all of those people that ever said you can't do this. just going away. i'm excited. i'm nervous, i'm scared. the weather is -- is iffy, but i'm ready for it. i'll take what i get. >> unfortunately, we're being forced to cancel the swim. >> you will still be in ironman. >> i'm disappointed and not angry. i'm still going to be racing for 14 or so hours. ironman, here i come. i don't think my race is any harder, it's just my race. a standard racing bike has 27-inch wheels. i have 20-inch wheels. so it takes more revolutions for my wheels to go the same distance. it's all i know. >> good job! >> racing longer distance is much more a mental challenge.

when i'm not at my lost and things are really hurting, i'm going to think about people in my life who tried their best to ridicule me and make fun of me. >> you are the hammer, baby! you are the hammer! >> and i think those people are going to motivate plea to buckle down and dig deep and keep going. >> go! you did it! [ cheers ] >> whatever body you have, male, female, skinny, tall, you shouldn't be judged by that outward shell. i think that's the message i hope that people take away. i'm really proud of what i did. i'm the first person with dwarfism to do a race. i'm 50 years old. it was amazing. very special time. i'm feeling pretty good. >> john young reached his goal becoming the first person with

dwarfism to be named an ironman. he's already training for next year with hopes of hitting the open water and completing the full ironman course. coming up, overcoming obstacles. literally. picking up for kyle. here you go. you wouldn't put up with part of a pizza. um. something wrong? so when it comes to pain relievers, why put up with just part of a day? you want the whole thing? yes, yes! live whole. not part. aleve.

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welcome back. with life throwing so man obstacles our way, why go seeking more? for most when we overcome an obstacle we're usually better for it, stronger, and smarter. maybe that's why obstacle course racing and ocr is one of the fastest growing sports. amateurs and pros sign up for to scale walls, crawl through

barbed wire, and jump over fire. for one professional racer, those hurdles represent more than just physical barriers. meet miguel medina, he's a professional obstacle course racer. >> i'm a professional obstacle course racer. what drew me to obstacle course racing is it was unique and seemed gritty and tough. >> obstacle course races have grown leaps and bounds the past few years. there's a big difference from the weekend warriors and an individual like medina who competes to win. >> i just eat myself into the ground at the gym every day -- beat myself into the ground at the gym every day. the pain will last for a day or maybe a year, but eventually it will subside. >> medina is no stranger to pain. >> at 16 i started noticing

weird twinges. if continued to get worse until i couldn't walk. i was in such constant pain. >> he was diagnosed with a problem in his spine. a debilitating condition known as congenital spinal stenosis. his only option was surgery. >> that whole sort of idea behind pain showing you a lesson, it's true. i knew at that point i needed to change almost everything about my life. i need to be able to move, to run, to be free. >> now, medina is one of obstacle course racing's top athletes. >> i've did well for myself. i mean, i think i've raced over 50 times now. most of my races have been top ten, top five around the podium. every race, i'm giving it everything i got. i have a good time and always try and learn from it. >> his next race, a punishing 45-kilometer challenge known as the spartan ultra beast. >> spartans, what is your profession? >> like an ultra marathon, basically, with obstacles on a

ski slope. >> if running 28 miles up and down a mountain isn't exhausting enough, runners are faced with 40 strenuous obstacles including 100-pound bucket carry, spear throw, and rope climb. for a competitor like medina, the race takes seven to nine hours to finish. what's started as another chance for a podium spot quickly changed. about 45 minutes into the race he stumbled and sprained his ankle. like years ago when he clawed his way back from surgery, medina pushed through the pain. >> all you got to do is put one foot in front of the other and tell yourself that you can do it. and that's what i did. >> don't get up. >> the only way they was not going to get that medal is if i couldn't finish. if my body was physically unable to keep going. i would have been on my hands and knees if i had to to keep going. >> miguel! >> it took him 14 hours, but

medina finished the race. >> if you quit, then you get nothing out of it. >> despite a debilitating injury, pain didn't stop him from reaching the finish line. as you'll see with the next racer, sometimes success is more about the journey and less about finishing a race. meet amy palmeiro-winters, an accomplished marathon runner and triathlete. >> i've been running since i was 8 years old. running is what i love to do and what makes me happy and part of who i am. >> she's also an amputee. the 44-year-old mother of two lost her leg in a 1994 motorcycle accident. amy has since competed in countless races. she even holds 11 world records. >> when i'm running, i'm always thinking about my kids. and just taking one more step. >> now she's training for one of the country's toughest ultra marathons, the angeles crest

100. runners have 33 hours to complete the grueling 100-mile course. most run all night, and many don't finish. for amy, the steep and narrow trails made it difficult to run on her prosthetic, and she missed the timed cut you've at mile 26. >> i feel great. i just missed the time cutoff. this is just as much of a success rather than a failure. if you can learn from it, you walk away a smarter person. i will absolutely be back. still ahead, what could be more motivating than a four-legged teammate?

the empire state building is the ultimate race. you get up into the stairs and try not to look at the floors. it's just a feeling of accomplishment. just self-affirmation. >> that's professional stair climber lisa ziegel who planned all 1,536 stairs of the empire state building in just 17 minutes and four seconds. look, it might not be your idea of fun, but she loves it. despite the pain. and loving what you do makes it easier to push your limits. just ask andy, he turned his childhood love of skateboarding into a career. becoming a professional racer in the world of long distance

skateboarding. andrew is a giant in the small but competitive world of long distance skating. >> kind of say it's between a cyclist and runner. >> at 39, he's the ultra skate world record holder skating over 300 miles in just 24 hours. >> there's no books out there was how to skateboard for 24 hours. so to was a lot of figuring it out. how to feed the body in a training program. >> want to confirm -- >> andres is a firefighter/pair medic in miami-dade. >> it's a physical, demanding job. it's a stressful job, and we need forms of stress relief from that. being out on the long board and racing was my answer. i love the competition in sport and pushing yourself past the limit that you didn't think you could do mentally or physically. the human spirit just wants to be challenged.

[ applause ] it's not easy to get off the couch andhallenge yourself. and having a teammate depending on you is probably one of the most tried and true ways to stay on track. our next racer found an unexpected teammate. a furry four-legged teammate. his dog. you've probably never heard of it. a sport that combines sled dog racing and cross country skiing. this is kajorin, and it changed a life. >> knocking that i was working with a teammate and not wanting to let her down. it sounds silly but gave me the emotional push to get control of my weight. >> let's get ready. i know the dogs are all ready to run. [ cheers ] >> johnson lost more than 80 pounds, and now races competitively every year in one of the country's largest races.

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welcome back. i'm dr. sanjay gupta. the thrill of victory, the agony of defeat. you may remember that line from the famous series "the wide world of sports." i tell you, it gets one thing wrong -- agony often comes as part of the race itself. there's something in the human spirit that makes it possible for us to overcome pain or any other roadblock that stands in our way. our final racer is doing just that with an incurable illness standing in his way. joe williams refuses to back down. to ride the iron horse is to have grit. and you have to have the mindset that you are going to suffer. >> the iron horse bicycle classic. it's a brutal test of strength and stamina for riders who face two 10,000-foot colorado mountain passes.

that's not all. they're racing against a train. when. >> when you start the iron horse, there are a thousand people around you. you hear the train. [ whistle ] and you look back over your shoulder and see the black smoke. than they let the bicyclists go. at that moment, you don't think about 47 miles and what's ahead. as we go up the mountain, they're all thinking about what it's going to take to get them over that first pass. it's the same for me, the same as it is for everyone else. >> for joe it's not the same. what he faces every day is far more challenging. >> receiving the diagnosis was shattering. the chief neurologist and said, joe williams, you have parkinson's disease. it was just as though a cannonball had struck me in the midsection. >> joe was diagnosed with spark son's six years ago -- parkinson's six years ago. the left side of his body would

freeze up. he saw a video of a patient riding a bicycle to reduce the symptoms of parkinson's. >> that little three-minute clip is what kicked me off. we got my old race bike out. i said, okay, darling, we're going to kick parkinson's butt. let's go. i think i made it about 400 feet before i tumbled down in the dirt. i got up, got back on the bike. i froze up, and off into the ditch again. this time, i crashed harder. >> the first few times out were terrifying. i wanted to be protective of him, he said, no, i have to keep trying. >> soon, joe was biking miles a day. >> thank you, joe. >> the journey from the beginning of falling until today has been hard. and today i'm 63, and i should have declined physically. but each year, i believe my

health is improved. to cross the finish line in simplerton, all you hear is people yeller for you as -- yelling for you as though you were the winner. >> go, joe, go! go, joe, go! go, joe, go! [ cheers ] >> his positive attitude got him everything that he's achieved today. it's an inspiration to me and a lot of other people. >> well done. >> i won. i beat the mountain today. i didn't beat that train. i'll never beat that train. but today of all days, i'm normal. >> eight races, eight stories of inspiration. showing us how the drive to compete against each other, even against our own expectations, can help us go further than ever before. i'm dr. sanjay gupta, thanks for

coming along with us on this "fit nation" journey. we hope we've inspired you to get out of your comfort zone and start one of your own. hi, everyone, live in the cnn newsroom, i'm poppy harlow. it is 3:00 p.m. eastern. today's high looeped meeting between president-elect trump and one of his fiercest critics, mitt romney, has just wrapped up. the two appearing moments ago at trump's golf club in bedminister, new jersey. their meeting the first of the day. we're told one top take that may have been up for discussion, the job of secretary of state. our phil mattingly is live in bedminister where the meeting just wrapped up. look, there's been no love lost between the two of these. donald trump has called mitt romney a choke artist. mitt romney has said that donald trump is a phony and a fraud. but the