(CNN) In Japan, where judo is more than just a sport, Kosei Inoue is no ordinary athlete.

Essentially unbeatable between 1999 and 2003, the half-heavyweight judoka won three world titles and Olympic gold, placing him among the greatest of all time.

Now head coach of the Japanese team, the 39-year-old is passing on his secrets to the next generation, proving just as successful off the tatami as he was on it during a stellar 10-year career at the top.

"We look at judo not only as a sport but as a 'budo,' or martial way," Inoue tells CNN.

"There is the competition -- we come to a World Championships and aim to win a gold medal -- but there is something far bigger behind this.

"By practicing judo every day, it really helps you win in life in general. In judo, you always get thrown and you always have to stand up. It's very similar to life itself."

Early years

Photos: A guide to judo The first judo school dates back to 1882 in Tokyo. Traditionally a Japanese practice, it has gradually spread across the planet and established itself as one of the world's most popular combat sports. Hide Caption 1 of 9 Photos: A guide to judo Literally meaning "gentle way," judo techniques harness an opponent's force to your own advantage by throwing and pinning them to the ground. Hide Caption 2 of 9 Photos: A guide to judo Judo was first seen at the Olympics in Tokyo in 1964, and a women's competition was added at the Barcelona Games in 1992. Hide Caption 3 of 9 Photos: A guide to judo No judoka has more world championships gold medals than Teddy Riner. In September 2017, the legendary Frenchman won his ninth title, before hitting double figures at an open weight competition in Marrakech. Hide Caption 4 of 9 Photos: A guide to judo "It is a sport that demands an irreproachable lifestyle," Riner tells CNN, "a sport that demands rigor." Hide Caption 5 of 9 Photos: A guide to judo On the women's side, Ryoko Tani's record stands out. The Japanese Judoka has seven world titles, and upon her retirement was hailed as the "best female judoka ever." Hide Caption 6 of 9 Photos: A guide to judo Majlinda Kelmendi tears up after being crowned Kosovo's first ever gold medalist at the Rio Olympics in the women's 52 kg weight category. Hide Caption 7 of 9 Photos: A guide to judo At 218 kilos, judoka Ricardo Blas Jr. (seen here on the right competing at London 2012) is the world's heaviest Olympian. Hide Caption 8 of 9 Photos: A guide to judo Russian President Vladimir Putin is a judo master, denoted by wearing a black belt. Hide Caption 9 of 9

Inoue, like so many others in Japan, took up the sport at a young age, working under the tutelage of his father.

The youngster would train relentlessly every day , only stopping when forced by his teachers.

"I was extremely motivated to do my best throughout my career," he says. "The meaning of judo is not just to win or lose, but to contribute to the betterment of society and always give back.

In judo, you always get thrown and you always have to stand up. It's very similar to life itself. Kosei Inoue

"The creator of judo, Jigoro Kano, outlined its two main themes: the development of the self and a contribution to society. When I practice judo, both as an athlete and as a coach, I always keep those in my heart."

Rarely defeated on the mat, some of Inoue's biggest challenges have come away from judo.

He lost his mother aged just 21, famously clutching a framed photograph of her as he stood atop the podium at Sydney 2000 a year later.

Legends of Judo: Kosei Inoue Bangkok 1998 Asian Games: Gold Birmingham 1999 World Championship: Gold Sydney 2000 Olympics: Gold All Japan Judo Championships 2001: Gold Munich 2001 World Championships: Gold All Japan Judo Championships 2002: Gold Busan 2002 Asian Games: Gold All Japan Judo Championships 2003: Gold Osaka 2003 World Championships: Gold

"I wanted to dedicate this win to my mother -- this is for her," the half heavyweight (-100kg) champion said at the time. "To me, she was the best mother in the world and I wanted the world to see her."

The entire family had shared a dream of Inoue one day winning Olympic gold; the realization of that ambition changed his life overnight.

"The Olympic Games is not just a sporting event; it's where the world unites," says Inoue, recalling his now-famous win over Nicholas Gill of Canada in the final.

"When I won at Sydney 2000 I was just 22 years old and still a university student. My life changed forever, but I was young and I felt like my career was just beginning."

Inoue won every single match at Sydney by ippon -- judo's equivalent to a knockout -- and the watching world expected him to dominate for many years to come.

The Japanese judoka didn't let up, taking home further gold medals at the next two World Championships -- held in Munich and Osaka -- as well as three consecutive titles in the open weight category at the All Japan Championships, defeating far larger opponents.

But he wasn't able to maintain his imperious form at the Athens 2004 Olympics, crashing out at the quarterfinal stage to Dutchman Elco van der Geest.

"So many people were focused on me and I disappointed them," Inoue reflected afterward, unable to come to terms with defeat. "I've never experienced anything as humbling and devastating in my life."

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Coaching

Inoue retired from judo when he didn't manage to make Japan's Beijing 2008 Olympic team in the heavier +100kg weight category -- though not before winning the 2005 Kano Cup and 2007 Tournoi de Paris.

Since bowing out, he has spent time in the United Kingdom, learning about other nations' styles of fighting.

Photos: 'You get thrown and you stand up again' Photos: 'You get thrown and you stand up again' Kosei Inoue is a judoka who has followed up a formidable career by becoming coach of the Japanese national team. A flagbearer for his country at the Sydney 2000 Olympic Games, he also won his first gold medal in the -100kg category. Hide Caption 1 of 6 Photos: 'You get thrown and you stand up again' Inoue defeated Nicolas Gill of Canada in the final. He carried a photo of his mother, who had died one year prior to the Games, onto the podium. "To me, she was the best mother in the world and I wanted the world to see her," Inoue said at the time. Hide Caption 2 of 6 Photos: 'You get thrown and you stand up again' Inoue coached Japan at the 2016 Olympics in Rio, where his team came away with 12 medals -- including three gold. Hide Caption 3 of 6 Photos: 'You get thrown and you stand up again' "We look at judo not only as a sport but as a 'budo,' or martial way," Inoue tells CNN. "There is the competition -- we come to a World Championships and aim to win a gold medal -- but there is something far bigger behind this." Hide Caption 4 of 6 Photos: 'You get thrown and you stand up again' Inoue delights the home crowd by throwing Ghislain Lemaire of France to win gold at the 2003 World Championships in Osaka. Hide Caption 5 of 6 Photos: 'You get thrown and you stand up again' Inoue sits dejected after a loss to Dutch opponent Elco van Der Geest in men's -100 kg competition at the Athens 2004 Olympic Games. Hide Caption 6 of 6

"I attained many coaching skills by observing the work of coaches from overseas," Inoue says.

"Judo hailed from Japan originally and, accordingly, was written with the kanji symbol, 柔 道. "Right now it is J-U-D-O, exemplifying the fact it has become a truly international sport."

As coach of Japan, he ensures that his fighters don't remain in their home dojos, but train all over the world.

"This is an extremely good opportunity to learn about other nations' styles of judo and incorporate them into Japan's training regiment," Inoue says. "My own time spent abroad was a wonderful, unimaginable experience."

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Having overseen a drastic turnaround in Japan's judo fortunes -- from just one gold at London 2012 to eight at the most recent World Championships in Budapest -- there are few more authoritative voices in the sport today.

How does the Japanese style, known for being very precise and technical, differ to others around the world?

"Every nation has their strong points," Inoue muses. "Each country has its own fighting style — for example, Mongolian sumo wrestling or Russian sambo — and this has all been funneling into judo at the world stage.

"The initial premise of judo is minimum energy, maximum efficiency; I truly believe that has been showcased in Budapest (venue for the 2017 World Championships.) The level of technique showcased by overseas players today is very high."

Tokyo 2020

Inoue was the proud carrier of the Japanese flag at the opening ceremony of Sydney 2000.

Inoue's next challenge is to sustain Japanese judo's success in the years running up to Tokyo 2020, when the sport returns to its homeland.

He could hardly have taken to the job better, but he isn't one to take anything for granted.

The battle will always continue Kosei Inoue, Japan judo legend

"I believe that the more you win, the more you have to lose," says Inoue. "Japan has many good practitioners, but their journeys are just beginning. It is one thing to win just once, and quite another to continue winning.

"As for the 'golden generation' of Japanese judo, we will do everything in our power to make sure they are ready to perform at Tokyo 2020, but the process doesn't end there.

"Coaches, athletes and the All Japan Judo Federation will work together to win all competitions."