When Sari Marsden first made her way to a gym in Hong Kong a decade ago, she had no idea it would trigger off a series of life-changing events.

The former radio deejay found a new career as a fitness and executive trainer, made her mark as a physique champion and even co-wrote Fit To Lead, a book on fitness and leadership.

"I never went to the gym before that. I was skinny and ate nasi padang all the time," she says, referring to steamed white rice eaten with an array of Indonesian dishes.

Her foray into the gym was prompted by her executive coach husband, who was then bitten by the fitness bug.

"It bothered me that each time we had a conversation, he would talk about what he did at the gym. He'd say: 'I did cardio, I did this, I did that' and I couldn't relate to what he was saying."

She decided to find out what the fuss was about.

Before she knew it, she had amassed an impressive resume of professional fitness qualifications from bodies such as the National Academy of Sports Medicine and International Personal Fitness Trainers' Association.

The 37-year-old is unusual in the fitness industry because she is also a Professional Certified Coach accredited by the International Coach Federation. She and her husband are founders of Sarius Performance, which conducts leadership guidance through a combination of executive coaching, fitness training and nutrition.

Decked out in black tights and a sleeveless top showing off her toned arms and sculpted body, Mrs Marsden has big sparkling eyes and a velvety voice.

The youngest of three children grew up in Pekalongan, a city famous for its batik artists, in Central Java.

Her father was a civil servant and her mother was a housewife and respected community leader.

"I was loud as a kid," she says with a laugh. "I knew I was smart and bright, so I didn't always hold my tongue. I was one of those who'd sit down with neighbours and tell them their cookies were not nice. My mother used to get so mad at me."

Her bluntness did not earn the all-rounder many friends.

"I was pretty much on my own and didn't have a best friend. Either they hated me or were jealous of me," she says.

At 16, she became a minor celebrity when she aced an audition to become the host of a radio programme for teenagers. She did it three times a week for nearly two years. "In those days, there was no WhatsApp or e-mail. Listeners had to come to the station and fill up a form if they wanted to make a request for a song. We used cassettes and CDs. There was no digital technology," she recalls with a grin.

Her dreams were too big for Pekalongan, so she left for Jakarta at the age of 17.

After obtaining a diploma in accounting, she started work as a radio deejay while pursuing a degree in mass communications at the University of Indonesia.

Adapting to life in the much bigger pond that was Jakarta took some getting used to.

"My confidence level shrank. I was insecure about myself. I was a small-town girl on my own in a big city. There was a lot of competition. It was tough," she says.

"I just felt that I did not have enough knowledge about the city or what people were looking for," adds Mrs Marsden, who invested in a personal development course to find out what her strengths and weaknesses were.

Despite her self-doubt, she was promoted to programme director after four years as a deejay at Radio One in Jakarta.

Candidly, she admits that she bit off more than she could chew when she took on the position.

Besides creating shows, beefing up listenership and leading a team, she had to be the conduit between staff and management. It was a frustrating yet edifying experience.

"I had ideas, but not enough staff to execute them. I realised how easy it was to start things and not finish them. I realised I was bad at saying no and I learnt I had to be committed when I say yes," she says.

A year later, she resigned from the post and went back to deejaying.

"When I resigned, I felt great relief. Not everyone can be a superwoman. I realised there were things I couldn't do and that it was okay to sometimes surrender."

Not long after, the opportunity to become a video jockey at a TV station presented itself.

"I liked being a VJ. I got my groove back and was starting to get famous," she says.

Fate, however, had other plans for her.

By then, she was in a serious relationship with Mr Marcus Marsden, 49. An Oxford graduate, he worked in change management and marketing at Unilever before becoming an executive coach.

His company The Works Partnership - an international training consultancy - had offered him a posting in Hong Kong and he had asked her to go along. "He made more money than I did so I had to follow him," says Mrs Marsden, with a hint of mischief.

The couple got married in late 2007 before she moved to join him in the former British colony.

When she started out in the gym, she didn't expect fitness to become an all-consuming passion.

But in just a couple of months, she started noticing changes.

"My shoulders were toned. I was losing weight but in a better way. I became fuller actually," she says.

Getting work as a radio deejay proved impossible in Hong Kong, so she used her time to get certified as a personal trainer. She also shadowed personal trainers at a gym before getting a job as a trainer in Fitness First.

The former radio station director had to start like any newbie: cleaning equipment, answering questions from gym-goers, trying to sell them training packages and helping them with gym equipment or routines.

"I just kept my head down and learnt. And then I got my first sale and started building my client base," says Mrs Marsden, who also scored a monthly gig hosting a radio programme in Javanese for Indonesian domestic workers in Hong Kong.

In a city where space is at a premium and gyms are small, the bubbly English-speaking Indonesian stood out at the Fitness First outlet in Central, where many expatriates work. It didn't take long before she got herself a healthy list of clients.

A female client got her interested in the link between the mind, body and emotions. Mrs Marsden noticed that the client was always looking down at the floor whenever she was asked to perform movements in front of the mirror.

A little prompting revealed her client had confidence issues.

"I started asking myself: Was there a time when I preferred to look down instead of up? Was I struggling with internal issues? Was I hiding something?"

She adds: "Who are the people in front of the mirror when I'm training them? What are their stories?"

After a chat with her husband - who is a senior partner in The Works International and another coaching consultancy Newfield Asia - she decided to pursue her coaching accreditation.

She wanted to help people get rid of barriers to success in their work and lives, which were also showing up in the gym.

Compared with Hong Kong, the couple's move to Singapore about seven years ago was much easier.

"I now have a job which I can carry with me anywhere," she says simply.

Her foray into physique competitions after arriving here was again serendipitous. The catalyst was a question almost all her clients ask her: How do I get six-pack abs?

"I needed to know how to get there too. Sure, I had the knowledge but if I didn't experience it myself, I'd feel like a fraud."

To push herself, she signed up for the National University of Singapore's Muscle & Fitness War five weeks before the competition in 2011. She enlisted the help of two of Singapore's most famous bodybuilding champions Joan Liew and Augustine Lee from Fitness Factory.

"It was really tough. It was December when I started preparing for the competition, and everybody was having fun during the holiday season," says Mrs Marsden, who had to keep to a strict diet and a punishing regimen of weight training.

But her iron will not only saw her through but also clinched her gold in the Model Physique category.

Over the next couple of years, she took part in several regional competitions. Among others, she bagged gold in the model physique category at competitions organised by the World Bodybuilding and Physique Sports Federation in 2011 and 2014, and the Singapore Bodybuilding and Fitness Federation in 2012.

Tearing up a little, she says putting herself up on stage was her way of showing herself, and others, that a woman can be strong yet vulnerable and graceful.

"I'm now done with competitions," she says, adding that her last championship was in 2014.

For the last few years, she has been beavering away at building up Sarius Performance, which she set up with her husband when they arrived in Singapore. The couple are Singapore permanent residents and their consultancy focuses on how fitness - mental, physical and emotional - can positively impact performance and leadership.

Being both a fitness and executive coach has opened many doors, says Mrs Marsden, who is a facilitator with Duke University's corporate education arm and an elite trainer with the Nike+ Training Club in South-east Asia.

In addition to one-on-one sessions with clients, she conducts fitness classes at a couple of studios, including Liv at Tanjong Rhu. She also designed the Women & Leadership Presence Workshop, which she conducts with another female executive coach in Singapore, Kuala Lumpur and Jakarta.

"I want to help people grow through fitness," says Mrs Marsden, who does not have any children but is not ruling out motherhood.

Every Thursday, she conducts a dance class for youth with disabilities at Mountbatten Vocational School. She has also volunteered at Aidha, a non-profit organisation that trains domestic workers in Singapore in self-development skills.

Writing Fit To Lead with her husband took two years.

"Fitness is not defined by how good you look. That's missing the big picture. The question to ask is: If I'm fit, what is my impact on others? That's what leadership is about."

Meanwhile, she wants to set an example, especially to women.

She hopes to help them "develop their strength, their flexibility, their grace to ultimately become women who are happy to be themselves in the world".

"This is my stand, the purpose for which I am emotionally connected."

•Fit To Lead is priced at $37.45 (including GST) and available at major book stores.