Estoro had trained with Willis. The Filipino pro mixed-martial arts fighter began in university and fell into Muay Thai after it became popular in his homeland.

The fighting style unlocked the world to him. He started competing around the globe, including in China.

"I fight not because I'm angry at my opponent but rather to display my skills," Estoro explains.

"This is my passion. I love this sport (Muay Thai)."

Van den Berg says the trio previously worked out of other gyms but finally found its own place.

They landed a partnership with the White Collar Boxing China organizers where Fight Republic trains amateur fighters in Beijing for a charity event.

Cat Nelson says she has been happy training at Fight Republic.

The dining editor of the news and city guide website Thebeijinger.com trained in Tae Kwondo as a child and discovered Fight Republic while training at another gym, Boxing Fusion.

"I think they do a really good job," she says.

"They're intense. But they're also very accessible. The idea is to bring people who have never done fighting or boxing before and make it (the sport) accessible for them."

Nelson signed up for the Beijing White Collar Boxing fight.

Magazine copy editor Colin Robinson has long been interested in boxing but never signed up for classes before he saw an ad for the White Collar competition.

Robinson says the trio is passionate about boxing and eager to pass on any knowledge and experience they can.

"They're always happy to take questions," Robinson says.

"They have a lot of enthusiasm."