Dressed in a neon yellow shirt and fluorescent orange shoes, Benny Ron ran softly along the asphalt sidewalk that stretches the length of Paki Avenue and the Diamond Head edge of Kapiolani Park. He practically glowed beneath the banyan tree canopy that keeps this end of the park in perpetual shade.

Ron isn’t the fastest runner here, in the day’s first hour of light, but that isn’t the point of his effort. Running is the reward for the 59-year-old Waikiki resident, who made his way through dozens of joggers and dog walkers.

He’s a marathoner, and this is where he trains every day.

Ron, an aquaculture professor at the University of Hawaii at Manoa who moved here from Israel, said his workout varies depending on the time of year. He’ll start with 5-mile runs and go as far as 20 miles by October to be ready for the Honolulu Marathon in early December. On this day in early July, his route was about 7 miles.

"It’s a very nice perimeter, very nice in the morning. Perfect," he said with a wide smile. "Lucky we live Hawaii, yah?"

Thousands of active folks like Ron have made Kapiolani Park Hawaii’s largest open-air gym. It’s the most highly used recreational park on Oahu, according to city officials. Folks of all ages, sizes and interests — runners, walkers, youth teams, tennis players, yogis and tai chi practitioners — are drawn to the 150-acre park’s three softball fields, rugby field, five soccer fields, 14 tennis courts and jungle gym-style fitness area.

We spent the day with them at Kapiolani Park on July 8.

AS A HANDFUL of people hit balls at the tennis courts on the makai side of the park at 7 a.m., Keith Wolzinger laced up his shoes to join them.

The 55-year-old airline pilot from Huntington Beach, Calif., is a regular at the tennis courts during his weekly layovers in the islands. On this day he was accompanied by his wife, Renah, 49, a state employee who decided to take a few vacation days and join him.

The couple do a lot to keep fit, from walking and swimming during their visits to Hawaii to biking when they’re home in California. Wolzinger said he plays tennis only during his brief stays in Hawaii because he’s usually too busy. He likes to play at Kapiolani because "the people are very friendly."

"And between the people that live here that play every day and the visitors that come from all around the world, this is like the melting pot of tennis," he said.

He’s played at the park for 12 years, meeting scores of new people on the heavily used public courts.

"They’re all friends," Wolzinger said of his playing companions. "And if I don’t know them, they’re friends anyway."

Nearby, Waikikiresident Mark Hansen sat on the grass behind the tennis courts enjoying the peace and quiet as he prepared for his daily one-hour run.

"I don’t want to preach but your health is everything," said the 47-year-old engineer. "Without it, you know, you can be living up the side of Diamond Head and driving your Mercedes and everything, and it’s not worth anything if you don’t have your health."

He would know.

About 10 years ago Hansen was diagnosed with bone cancer and had cancerous tumors in other parts of his body. At one point he was close to death. "I couldn’t even walk," he said.

Treatment cured him, but his personal drive got him back on his feet.

"From there you start walking," he said. "You walk a little bit and you build from there. You build up and up and up, and then you get your health back. You learn that you have to exercise and eat properly and do all the spiritual things and everything else."

His morning runs are an opportunity for reflection.

"Actually, I’m glad I got cancer. It saved my life," Hansen said. "It sounds strange. It wakes you up to reality and makes you realize what’s important in life, what really matters. So, it’s a good thing. I’m really happy."

MARK OKITA is 54 but could easily pass for a man 10 years younger due to his fit physique. Standing by the fitness station near the tennis courts around 8 a.m., the McCully-Moiliili resident described his two-hour workout routine: one lap around the park, plyometrics (jump training) and upper-body work, doing pull-ups and using his resistance bands with the fitness station equipment to do most of the exercises you’d see in a gym.

"You get the fresh air, the sun," Okita said. "It’s for your health, right? So why not make it a total experience with the trees and the birds and the wind and the sun?"

He said he loves Kapiolani Park because of the outdoor setting and how well it’s maintained. But he also pointed out how all three of the fitness area’s workout benches are worn down — two were being held up by cement bricks, another had collapsed and yet another had sharp, rusted edges.

Okita suggested it should be expanded or perhaps another one built at the park due to heavy use. During the afternoon, he said, it’s so busy that lines often form to use the pull-up bars.

But even with the park’s flaws, Okita treasures his morning routine.

"This is my playtime," he said. "This is fun."

Fitness canbe a family affair for some: At 9 a.m. Nathan Carl, 38, did arm curls using resistance cables while his wife, Kimber, 35, lunged and squatted on the park’s soft grass while holding the Honolulu couple’s 1-year-old son, Noah.

"In the mornings is the best because you’re strongest in the mornings," said Nathan Carl, owner of the video production company FreedomRiding.com. The Carls do mostly calisthenics using their own body weight as resistance.

He said the reason he loves Kapiolani Park is the crowds of people and its natural beauty. His wife agreed.

"It’s nice because you got the full ocean view," she said. "It’s beautiful."

EXCEPT FOR a group of schoolchildren enjoying playtime, Kapiolani Park’s main fields have been mostly unused on this day. But at 11 a.m., as the temperature surged into the upper 80s, six men practiced hitting and fielding softballs.

Dylan Linkner, Marnie Aduca and their fellow Moana Surfrider co-workers were there to practice for a hotel league tournament on Maui.

Aduca, 51, pitched to Linkner, a 27-year-old former wide receiver on the University of Hawaii football team. Linkner, dressed in gray sweats and a Los Angeles Dodgers baseball cap, sent many of Aduca’s pitches sailing into the outfield where other teammates waited to snag each one from the sky.

The guys were upbeat, mostly because they couldn’t stop making fun of one another. But they couldn’t escape the heat.

"This is torture," joked Aduca, "not exercising."

Not much happens at Kapiolani Park when the sun reaches its zenith. It’s just too hot for most. By 3 p.m., though, the baked fields typically host swarms of young soccer players. On this afternoon, athletes from a dozen different teams practiced ball techniques.

"This park is so important for the teams. Soccer is a year-round sport," said Kerry Miike, a coach with the Honolulu Bulls Soccer Club.

Miike arrives at the park about an hour and a half before practice so he can claim a spot.

"We have to fight for space," he said. "It’s on a first-come, first-served basis."

He worked with two of the boys on the team, Dominic Gusman and Braden Nihei, a pair of 12-year-olds whose broad smiles, laughter and enthusiasm demonstrated their love for the sport. They’ve played soccer for half their lives.

Kelsey Baker, a coach for Leahi Soccer Club, brings her team to the park a couple of times per week. "The park is awesome because there’s always so much going on," she said. "I love this place. I grew up using this park and played soccer here myself."

THE LATE afternoon attracts other fitness enthusiasts, among them Karen Kramer, a 32-year-old Honolulu resident who works as a special-education teacher and personal trainer. She arrived at 5:30 p.m. to join friends for their weekly intense workout at the exercise stations.

"I’ve been coming for about a year now," she said. "People that you can count on always show up."

Burpees, pull-ups and medicine ball exercises are part of the routine that Kramer and her friends embrace. Workouts average 45 minutes.

"The great part about it is it’s free and people encourage one another," Kramer said.

William Moschell, a Honolulu resident, has belonged to the group for a few years.

"We take turns creating the workouts, so it’s always a little different," he said.

The group was organized more than five years ago and started with about 50 members. Nowadays it varies from a handful to more than a dozen. At this session there were seven.

"This place was packed when we first started meeting," said Moschell, a 39-year-old art director. "We started making the workouts harder, and lots of people stopped coming."

Juggling a demanding work schedule and the activities of her busy children doesn’t leave much time for Jaylene Chee to squeeze in workouts. But give her an hour for a run and she’s all in, shades wrapped around her game face and a portable music player strapped to her arm.

The solitude of a run helps Chee, a 44-year-old mother of two from Kapolei, regain her focus for her mommy duties.

"The summer months allow me to stay out later," Chee said.

A volunteer coordinator at a nonprofit organization, Chee runs from her office, which is not far from Kapiolani Park.

She usually pounds the pavement and enjoys the scenic route around the park after work — it was 6:15 p.m. on this day — but sometimes she heads out during her lunch hour. She tries to work out at least three times a week.

"After sitting at my desk all day, the fresh air seems to be a refresher for me," Chee added. "If I don’t exercise, I am exhausted by the time I fight traffic. I often don’t want to go because I’m tired, but after I’m done I feel 100 percent rejuvenated."

AS DUSK brought an end to another day at Kapiolani Park and folks headed home, one group seemed unfazed by the departures: Bharat Das and his yoga students, deep in meditation after more than an hour of traditional and sometimes strenuous poses on the grass near the Diamond Head end.

The 75-year-old Das, who opened the first yoga studio in Hawaii in the early 1970s, leads the open class every weekday evening at 5 p.m. and on the weekends at 8:30 a.m., beginning with hatha yoga and breathing exercises. He ends with meditation. Das has taught under the same tree in the park for the past 20 years.

Ryan Peters, 28, a visiting Hilo resident, kept his perfect meditation posture for 15 minutes while other people had to stand up and walk around.

"It’s torture but it gets better over time," he said.

Yoga is a tool for self-realization — a spiritual transformation, said Amy Kogut, a 66-year-old Honolulu resident.

"The practice deepens our sense of self-love and the reverence to treat the body as a temple," Kogut said. "It’s not just a form of exercise."

The other participants agreed that it’s a perfect way to end the day.