Egan Inoue has come full circle since watching his parents work out through the windows of the iconic Spa Fitness Center on Punahou Street in the 1970s.

Today, his 76-year-old parents, Errol and Naomi, still exercise at the same location at 1212 Punahou St., this time run as a boot camp by their son.

The retired mixed martial arts fighter and renowned jiu-jitsu champion turned fitness instructor recently expanded his popular boot camp classes into the 10,000- square-foot Punahou Street location, more than triple the size of his oldMoiliili gym, where the lease had expired.

“Punahou spa opened up the first big mainstream gym for everybody. It was real interesting for me as a kid,” said Inoue, 53, who ran a gym for fighters in Halawa in the mid-1990s before starting a small outdoor boot camp at Kapiolani Park. “For me, from when I was 16 years old, fitness has been my life. That’s all I study, that’s all I do, that’s all I care about.”

With about 1,200 members, Inoue’s business has grown tenfold since he started boot camp with about 100 people in a small Manoa gym in 2010 after some convincing by his wife and gym co-owner, Marcia Inoue.

“It took a little while to convince him. He was like, ‘I’m not going to do aerobics,” she said. “I’m like … just teach them how you train for fights and your conditioning.”

Though well-known in the MMA circuit, it wasn’t his reputation that initially helped boost his business.

“In the beginning it actually hurt us because people were so scared that he was an MMA fighter. They don’t think they can train with him, but then they realize how fun he is to train with,” Marcia Inoue said. “Now he’s built his name over the last 10 years of not being just an MMA fighter, he’s kind of like a fitness fighter and that’s really neat to see.”

Egan Inoue has won world championships in Brazilian jiu jitsu and MMA, as well as racquetball. He often shares words of inspiration and strategies on how to endure through pain during intense 30-minute workouts that end just when members aren’t able to push any further.

“They work every muscle in the body and change the exercises every single day,” said Julie Ford, a 47-year-old Kakaako resident who’s been a member for the past four years. “Most of all, Egan and staff constantly push us to work harder and aim higher. They often share stories about their personal lives and how they’ve overcome adversity — making it the perfect positive thinking and challenging workout program I’ve ever done.”

Memberships can run up to $200 a month, though the company runs frequent promotions on social media that begin at $79 for a 21-day jump start program.

“Our memberships are not cheap. We believe when you invest in yourself you’re going to show up more. For us it would be better to have (fewer) people invested in health and fitness paying a little more than for us to have triple the amount and only a third of them using their membership,” Marcia Inoue said. “To us that’s not a sustainable model. You have to have people in here loving what they do to get them to keep coming and to refer people.”

The couple has cultivated a family-like environment where members help keep each other accountable. They have an active Facebook page for members who call each other out when they are slacking in their fitness routine and share stories about their struggles.

“You don’t feel intimidated when you come to the gym. That’s why people fall out of fitness because they don’t have that kind of accountability,” Marcia Inoue said. “If they don’t show up for a week we start calling them. Most gyms if you don’t come for a year you don’t hear from them, you just keep paying your dues. We’ve been really lucky to have the success that we have that comes with having just amazing staff and really great members that look out for each other.”

The Punahou spa was the first fitness center of its kind in Honolulu when it opened in 1974 and has had a string of owners since the dramatic increase in competition in recent years as larger chains such as 24-Hour Fitness vie for a share of the market.

The state’s longest-running gym at the time — then known as Punahou Spa Fitness — abruptly shut down in 2012, leaving hundreds of members in limbo. It was reopened a couple months later under a new owner before succumbing to the heavy weight of competition again in 2015. More recently, the location was turned into a rock-climbing center.

The Inoues have invested more than $200,000 to renovate the space, filling in the original indoor swimming pool and remodeling the restrooms..

There’s now a children’s area and rooms for martial arts, yoga and boxing, locker rooms and showers. A separate space is dedicated to “next-level boot camp” with more strength training and sports conditioning using weights and other equipment. In addition to Honolulu, Egan Inoue runs boot camps in Aiea and Kailua.

He said he hopes his turn at the former Punahou spa will be as successful as the original gym.

“With all the different fitness gyms opening up, it seems like (the market is) saturated, but I think we have our niche,” he said. “We definitely like having little groups and we definitely try to have the best customer service. That is what our goal is,” Inoue said. “I think there’s a place for everybody. We got over a million people here. There’s definitely enough room for everyone in fitness.”