Tiffiny Hall was born to fight. She kicked butt as the smiling assassin Angel on TV seriesGladiators, then became best known for her role as a hard-nosed trainer on The Biggest Loser, where she whipped eventual winners, the Duncan family, into shape.

Hall is the feisty girl who grew up at a martial-arts dojo and now visits school kids dressed as a ninja to promote health and build-self esteem.

She’s also the petite blonde with the temperament of a shaken-up fizzy drink who has found it tough proving there’s more to her than meets the eye.

Hall is now fighting for a new kind of respect as she focuses her infinite energy on writing. When we catch up at an Essendon coffee shop, her enthusiasm is infectious.

“Everything I’ve done in my life has been about building a profile, a readership and an audience so that one day I could bring out my fiction,” Hall explains.

“I was always writing, and that came first. People didn’t know that side of me because they only saw the athlete on television. It’s been something to overcome but it’s also been something that’s helped my books.”

In 2012 she published her first novel, White Ninja, about a 13-year-old girl called Roxy Ran who realises she is turning into a powerful ninja after saving a kitten from the school bully.

Hall used her then 11-year-old brother as a guinea pig and figured if she could entertain him for more than a few minutes she was on the right track.

The sequel, Red Samurai, followed this year and the final part of the trilogy, Black Warrior, is being edited for release in 2014.

“It’s sort of bittersweet,” Hall says of finishing the series. “It’s exciting to wrap it up but I’m also in love with my characters and want to keep it going.”

The parallels between Hall and her characters are unmistakable.

The 29-year-old grew up in Essendon and was born into a martial arts family.

Her father, Martin, an international competitor and one-time Olympic coach, started Hall’s Taekwondo centres in Brunswick in 1984.

Her mother took up the sport and was one of the first women in Australia to get her black belt. By the time Hall was 12 she too had secured the rank.

Today she credits the sport with instilling in her a resilience that has been unwavering.

“No matter what I set my mind to I sort of had this black belt mind-set,” she says. “It taught me to be a good coach and a good trainer and led me down the path of The Biggest Loser and working with and helping people.”

Hall still trains regularly at the Brunswick headquarters.

“I have long-time friends there and it keeps me so grounded because even when I went off and did telly I would still come back and get beaten up in taekwondo.”

Hall’s passion for writing was sparked in her youth as a student at Lowther Hall Anglican Grammar School.

It certainly helped that famed young-adult author John Marsden then doubled as her grade 6 English teacher.

She describes him as a prolific influence in her life and the inspiration behind her pursuing writing.

“He was my teacher as I was reading them,” she says of his much-loved books. “He was the rock star of my childhood.”

The pair kept in contact, and when Hall wrote her debut White Ninja it was Marsden who first laid eyes on it.

She screamed the day he gave it a public tick of approval.

Marsden recalls Hall as a lively student who he always believed would achieve success.

“Tiffiny certainly stood out,” he says. “Not just for her prodigious talent but because of an energy one sensed when working with her. She was committed, focused, intense.

“To see someone I’ve taught making a success of writing is more exhilarating than seeing my own books published.”

From the beginning, Hall was looking long-term with her writing career and purposely set about building a brand to make it easier to get published.

She studied journalism and interned at the Herald Sun, tackling everything from court reporting to travel writing, before answering an ad in the paper to become a “Gladiator”.

“I told my family I got a journalism gig in Sydney reading the news because I didn’t know how they’d react. The next thing they saw me in boxing boots and Lycra on the telly.”

Her career snowballed and her presence on Australian television screens has been constant since.

“A lot of people still remember the show [Gladiators]. It haunts me because I want to be remembered for writing my novels and people are like ‘aren’t you Angel?’.”

Hall became a household name when cast as a trainer on The Biggest Loser, the role earning her a Logie nomination for most popular new female talent.

“You’re working with the best trainers in Australia and the contestants are so brave and courageous, coming on to TV to lose weight. Seeing the transformations, not only physical but emotional, it was life-changing to them because then they decided to go after their dreams.”

Hall herself is reaching for the stars.

She’s recently returned from a two-month trip to Los Angeles where she “put the feelers out” for future television possibilities such as working with The Biggest Loser US.

Again, her underlying goal is to use television as a vehicle to pitch her books to a wider audience.

“The Ninja novels are quite popular and I would love to see them turned into films or a cartoon series,” she says, beaming.

Hall said goodbye to the Australian version of The Biggest Loser this year to focus on her writing but has left the door ajar on a return.

Biggest Loser was a huge chunk of my life but I have to say the most rewarding thing was publishing my first novel.

“I didn’t want to compromise the quality of my writing for the television. It [writing] has always been my greatest dream.”

At home in Essendon, Hall writes throughout the day, ploughing through about a thousand words at each sitting.

Her boyfriend, radio and television personality Ed Kavalee, is doing the same with scripts.

“It’s very funny that we both sit at home and write. He’s writing films and I’m writing books. We write at different ends of the house so it all sort of works out.”

Except, of course, when she gets writer’s block. “I have a baby grand piano at home that I bash whenever I’m frustrated and that has helped me to relax. A lot of people say ‘you must go to taekwondo and smash it all out?’. And I’m like ‘nuh. I take it out on my poor piano’.”

Hall trains early in the morning and sticks to a strict fitness regime. She doesn’t count calories and says healthy eating as the key to weight management. She does, however, confess to having a sweet tooth, listing lollies, biscuits and chocolate as weaknesses. It’s her birthday later this week and she’s already thinking ahead to the buffet.

Maybe she’s human after all.