Three minutes.

It’s the length of a round in boxing.

It’s the length of the various exercises used at Fighters Unlimited for both aspiring boxers and those wanting one of the best fitness workouts around.

Think Rocky Balboa meets U.S. Marine Corps. That’s the program developed by Jack Johnson, a chief warrant officer stationed at Marine Corps Base Hawaii the past 10 years.

“Some of it comes from personal experience,” said Johnson, who began boxing while growing up in Kansas City, Mo. “Some of it is from being a certified trainer through USA Boxing.

“I’m always learning new techniques from friends and colleagues … not to mention the Marine Corps. They know workouts.”

Johnson joined the Marines out of high school with the goal of making the Corps’ boxing team. He served for four years, got out only to return after a few years for a second stint and “was lucky to be stationed in Hawaii 10 years ago,” the 40-year-old said.

That’s when Johnson started Fighters Unlimited on the base in Kaneohe. The demand kept pace with the resurgence of the sport until about a year ago, when the boxing club outgrew the base and moved a few miles away to the industrial park off Kapaa Quarry Road in Kailua.

“More people were wanting to come and sometimes it was inconvenient (to get on base),” said Johnson, who had to close the club on base during his six deployments to Iraq and Afghanistan. “We took the leap here.

“We do compete as a boxing club in the local events, but we also have people who train for the exercise and the fun. You don’t have to get in the ring unless you want to. People say it’s the best workout they’ve ever had.”

There are 172 active members, ranging in age from 8 to 57. It’s a diverse mix, according to Johnson, of military and civilians, adults and kids, males and females; it can be a revolving door, due to military comments.

The “open gym” concept makes it attractive for those unable to commit to an exact time for a class. There is a set routine for the day — a list of 10 activities with varying repetitions — but the 70-minute routine begins when the participant arrives.

There are a few givens. There always is stretching and there always are the three standard exercises: jumping jacks, ducking drills and side-to-side footwork.

“Everyone wants to come in and hit something right away,” Johnson said. “But we make sure they get the footwork down before they get on the bag.”

Footwork is the basis for Felicia Cazares’ two passions: boxing and dance. The 18-year-old is the daughter of Fighters Unlimited head coach Felix Cazares but the freshman at St. Mary’s (Calif.) College says, “I actually hated boxing, I always wanted to dance. I grew up with the sport, my dad was a coach, my mom (Beth) was a judge. I finally told my dad I wanted to try it.

“I love it. It definitely helps my dance, my stamina, my coordination skills. I’d recommend to women. It’s self-empowerment; you gain so much self-confidence. Getting into the ring takes courage. You overcome your fears and it carries over into the other parts of your life.”

The Sacred Hearts graduate carried the sport with her to college, where she has become an assistant coach for the fledging St. Mary’s boxing club. She helps train six male students and “it’s showing them discipline and what hard work can do,” Cazares said. “It’s a full-body workout, but you get so much more out of it.”

Cpl. Chris Ingram found a sport at which he could excel. The 26-year-old, who ran track and played football in high school, learned about the boxing club during an intramural football game on base.

“I found out about it by accident and I found something I was good at,” said Ingram, who also is a martial arts instructor. “In order to be serious, you have to commit your whole lifestyle to it. Eat right. Sleep right. I can’t think of another sport you have to dedicate your lifestyle habits to. I come every day the gym is open.”

Currently, Fighters Unlimited is open from 5 to 8 p.m. Monday through Thursday and 9:30 to 11:30 a.m. Saturdays. Johnson is hoping that will change in two years, when he retires after 20 years of service.

Asked what he’ll do when he gets out, Johnson said, “Open earlier.”

The gym has hosted amateur boxing cards, with floor seating for 272, as well as served as the venue for an occasional rock concert put on by local bands.

Johnson said he wants to continue to be part of the community by giving back. One future event he hopes to hold is a “Guns & Hoses” charity fundraiser that would feature boxers from the Honolulu police and fire departments.

Now that the gym is off-base, Johnson is able to have his son Matt and Felix Cazares run the gym while on deployment.

FUBC was to host an amateur match event next Saturday, but because of the state championships Jan. 13-15, it has been rescheduled for February.