Always a huge sports enthusiast as a child, Tallaght native Mark Casserly took his love of taekwondo further than most by training to Olympic standard at a Korean university.
"When I was growing up, my father watched all these epic, alpha-male movies and I recalled that as a kid," he says. "It was probably an unrealistic expectation for any young boy, but you dream big. At the age of 13, I wrote in my diary that I wanted to get into martial arts. It was purely recreational, but the better I got, the more I was told by coaches that there was something there."
After training in various high-performance camps across the globe from Iran to Las Vegas, he soon had the 2008 Beijing Olympics in his crosshairs. And, like any elite athlete training for the ultimate tournament, that meant an unparalleled level of determination, discipline and sacrifice.
"I was sent to Olympic selections and was eight years in training," says the 31-year-old. "I got a sports grant and a travel grant. Because taekwondo is the national sport in Korea, my coach decided to send me on a scholarship to a university in Seoul. The great thing about Kyung Hee University was that they had trained so many taekwondo champions there, and I can see why: it was very militarised, and very painful training. I missed Ireland a lot at the time, but made sure to talk to home at least once a day."
Needless to say, training in Korea was something of a culture shock for the then twenty-something, and a tad different from his undergraduate course in DCU. Not only was Mark spending four to five hours training in taekwondo every day, he was learning Korean for almost three hours a day.
Ultimately, there was much in the way of pay-off: not only was Mark introduced to what he calls a "high work ethic" and developed many good habits, he also learnt the true philosophies behind the sport. Soon enough, the Beijing Olympics qualifiers drew nearer.
"To qualify for Beijing, I was sent to fight in Paris," says Mark. "I'd won one fight, then was fighting against the reigning Olympic champion. I lost to him by three points, which ultimately sent me home."
After spending much of his adult life with an eye firmly trained on Olympic glory, it is safe to say Mark found it tough to accept that the Olympic experience was just out of reach.
"I sat in Dublin Airport for three hours after knowing I didn't qualify," he says. "I felt I'd let everyone else down. I could intellectualise it and tell myself that no one put me under pressure to succeed, but I felt for my family.
"I went home to re-evaluate things, and it took some time to transition and accept eight years of ridiculously high-intensity training, not to mention personal and professional sacrifice. The problem with Olympic training is that you don't see anything other than the medal as a marker of success, and I began to realise this was an unhealthy way of looking at things."
Retiring in his early 20s but still harbouring a love for martial arts, Mark turned instead to another combat sport, Muay Thai. To many, this may not seem like a significant leap, but scratch the surface and it becomes clear the two are very different disciplines.
"It's like asking someone to go from tennis to swimming," he says. "They call it the 'art of eight limbs' (because of the combined use of fists, elbows, knees, shins and feet). The level of physical training needed is very high, but in another way it's like a game of chess. And the risk of injury is quite high. There are stitches, there's blood, there's a high knockout rate. It can be quite vicious and beautiful at the same time."
Just as his Muay Thai career was gaining traction, Mark was facing yet another personal tragedy – the death of his father, Neville, from cancer. He needed to take his frustrations out somewhere.
"It worked for me because I was at an age and point in my life where I needed to vent," he says. "I didn't have to think of winning, or medals, I just wanted to fight."
At the ISKA Championships in Citywest in May last year, Mark knocked out reigning champion Marcus Davis with a brutal kick to the neck.
"I'm still friends with a lot of my opponents," he says. "It's very professional and we chat afterwards. It's a vicious sport, so you certainly don't want to put someone in a wheelchair. A KO is all well and good, but you hope they wake up safe.
"People see Muay Thai on TV and think it looks barbaric, but the philosophy is quite unique. Despite the stereotype, they're very educated and intelligent people. No doubt there are brawlers and people who love to fight, but those who like to swing firsts tend to have no philosophy. They retire early, often in drastic circumstances. They go out with a bang, because that's how they came in."
These days, Mark juggles work as the business manager of a Naas health club with his career as a fighter.
"If I'm in training for a fight I really only work and train," he says. "I'm in bed at 9.30 every night so I can recover for my morning session. I would train twice a day, six days a week, with the first session before work and the last one directly after.
"Socially, I would go to the cinema a lot on the weekends to kill the time. However, you're just filling up time before your next session, and you become quite a recluse. I'm fortunate to have people around me who understand this way of life."
Describing his weekly regime as "robotic and measured", Mark is certainly dedicated. He eats 1,600 calories on non-training days (2,500 on his six training days) and on a daily basis takes 150g of protein, four litres of water and five cups of green tea and weighs himself twice. He may have left behind the Olympic dream, but it would appear that old habits die hard. The post-career plan is to coach and spend time with friends and family, but for now, Mark is keenly aware of how fighting in the ring has helped him hugely with his own personal battles.
"For me, I train as if my next fight is my last – and it may well be, with such a high rate of injuries in bouts," he says. "I find that the fighters who enjoy training on a social level outside of the rigours of competition last longer. Their attitude regarding health, nutrition and overall well-being gives them a stoic ability to handle adversity."