Now based in Roxburgh, she talks to Central Otago reporter Jono Edwards about using the martial art to bring people empowerment and confidence in both her Teviot Valley town and throughout the world.
When she first had the chance to fight on the world stage, Sue Glassey was not sure she was ready.
In 1998, she had the opportunity to enter an international tournament in China after one of the other New Zealand women in her weight division became pregnant.
She was encouraged by her trainer, who told her she might not get a chance like that again.
''And I ended up winning it. I won a world title before I'd won a New Zealand one. Then I came back and won one in New Zealand.''
Miss Glassey (46) took up the sport about 25 years ago through the influence of her brother.
In the traditional Thai martial art, practitioners uses their ''eight weapons'' of elbows, knees, shins and fists to outclass opponents.
''My favourite part was the tactics, learning people's tells. It makes you really take a look at yourself. If you slack off in training, you're going to lose. You have to be incredibly fit for your brain to keep working.''
When she started, while living in Palmerston North, she was not attracted to fighting in tournaments.
''But when you get better at things, it's just another challenge.''
After only nine months of training she won her first tournament, at the Eltham Town Hall in Taranaki, in 1993.
''That kind of cemented me doing it. I thought I was pretty cool.''
Since then she has won various world titles.
Miss Glassey recalls women fighters were far less respected than the men when she started.
''Female fighting back then didn't have any prestige. It was seen as a bit of a joke.''
With only about 20 women Muay Thai fighters in the country, she ''ran out of people to fight''.
Because of this she began boxing as well and won a South Pacific title and a New Zealand title.
In 2002, she started the New Zealand chapter of the International Federation of Muaythai Amateur and acted as its president for 10 years. She remains Oceania president.
One of its main goals is to get Muay Thai on to the greatest world sporting stage.
''Last year, we got it accepted in the Olympics. We've been told in 2024 it should get a chance to be a trial sport. We've got to prove a lot of things, like that it's anti-doping, improves social development, empowers females and people with less power. We've also got to prove it can pull crowds and that it's international. That it won't just be Asia that wins.''
One triumph on the political side of the sport was changing the rules of international tournaments to allow sports hijabs and uniforms which cover the arms and legs. This allowed the participation of Muslim women who opted to be more covered as part of their faith.
Miss Glassey has worked with the United Nations to use the martial art in female empowerment and anti-violence campaigns throughout the world.
''It brings a lot of mana to females and brings respect, which filters down into those communities.''
Since 2015, she has lived in Roxburgh as a teacher at Roxburgh Area School, but says she did not originally plan to start coaching there.
''But some people started badgering me to do it. Mykayla really wanted me to.''
Through her training, Roxburgh Area School pupil Mykayla Robert (16) is now in Thailand at the world amateur championships.
''She'll be up against people who have been training for years. But it's not about winning, it's much more about her having that confidence to go over to Thailand by herself and do something like this.''
While there still is a way to go, women in the ring have become a lot more accepted than when Miss Glassey started, she says.
From about 20 female Muay Thai fighters 25 years ago, the number now would be in the hundreds.
''It's partly a generational thing. Most of trainers now are my age. They understand how hard it is for anyone to get in the ring.''
