After entering an international taekwondo championship on a whim, a Moncton man who battled a near fatal illness just a few years ago, has come home with a gold medal.

Sam Johnston recently returned home from a trip to South Korea as champion in the Senior Master Integration Division at the World Taekwondo Championships.

"I was on top of the world," said Johnston of his win.

Bringing home a medal was not the 52-year-old's plan. Competing was not even part of the plan, but Johnston figured since he was going to be in Seoul taking part in the international masters instructors course, he might as well enter the competition.

"I mustered up the courage to enter. I hadn't competed since I was 38."

Johnston has been a martial arts taekwondo practitioner since he was a teenager. He is now an instructor who has achieved his master's rank in eighth degree black belt.

A senior manager with Corrections Canada, he has also taught a number of students in Miramichi and Moncton.

Life changing illness

Over the years, Johnston competed in eastern and central Canada and in the eastern U.S., winning numerous competitions and rankings. He was planning to compete in the world championship competition seven years ago but two months before the event, he got sick.

"During my classes I was feeling very tired. I was getting winded easy and I just didn't have a lot of energy."

Johnston went to the doctor and a blood test revealed he had leukemia.

He spent the next four months in the hospital in isolation getting ready for stem cell transplant. Johnston's brother was a viable match.

Sam Johnston during his fight to beat leukemia. (Sam Johnston/Facebook)

"He's very different than me personality wise but he was a perfect genetic match blood wise."

Johnston describes this time in his life as gruelling and difficult as he underwent various treatments to treat the disease.

"It took a lot out of me. I lost a fair amount of weight and I was weak but I was recovering."

But then his progress stopped, and Johnston developed graft versus host disease.

"I traded the leukemia for another disease. They fixed the leukemia but my brother's blood started to attack my internal organs of my body."

Close to death

Johnston's immune system was compromised and he developed several infections. He lost the use of his arms and legs.

At one point, the oncologist told his wife he wouldn't survive.

"I refused to go to palliative care. I refused a feeding tube. I was determined to get better."

Johnston said little by little with intensive treatment and extensive physiotherapy, he got better.

Road to gold medal

It took Johnston 18 months to recover enough that he could return to teaching and training in taekwondo.

Then with his immune system built back up over the past four years, Johnston felt it was safe to travel, and to compete.

"I didn't enter the competition to lose, but at the same time I didn't expect to win. I knew it was a long shot to win a gold medal."

Johnston made it through the preliminaries and got into the finals, finishing in the top three. He defeated the defending champion from China in overtime.

Sam Johnston won the gold medal after going against the defending champion in overtime. (Sam Johnston/Facebook)

"I was just on top of the world. I was pleasantly shocked. To win a gold medal at a world championships at the stage of life that I'm in after what I've been through was just an unexpected blessing that I'll never forget."

Johnston said his achievement shows that if you live a clean life, are healthy and fit, anyone can overcome any challenge.

"It can truly serve you well. It certainly did for me."

Johnston plans to continue training and will be returning to South Korea in a year to defend his world title.