Want to be serious about getting fit? You can join a fitness class - or better, teach one.

From ballet barre and exercise bootcamps to yoga and pilates, the fitness industry is attracting more practitioners who want to be certified instructors.

Some are training on top of full-time jobs, while others give up lucrative careers to go into fitness full-time.

Three fitness junkies tell The Sunday Times why they are happy to have turned their passions into professions.

Rapport with students keeps her going

Every Monday, Wednesday and Thursday, writer Joie Goh is up at the crack of dawn to work - not at her computer, but at a ballet barre studio in Tanjong Pagar, where she teaches a class at 7am.

The workout, which is a mixture of ballet postures, cardio and strength training done to music, has often been dubbed the Victoria's Secret workout because it is practised by models to build long and lean muscles.

After the class finishes at 8.15am, Ms Goh, 30, goes to work at a publishing house as a features and beauty editor.

"I love being able to start my mornings on such a positive note and now I see fitness as both a passion and a fallback career for myself," the singleton says.

She used to do ballet and gymnastics as a child, but in her adult life kept fit by sporadically running on the treadmill.

In March last year, she decided to revisit ballet by taking barre lessons at local studio WeBarre and was sufficiently hooked that she signed up to learn to be an instructor within three months.

She spent $1,000 on a gruelling five-day training stint, where students were not only taught movements and techniques, but also about posture and anatomy by a master trainer from Australia.

After graduating with her certification, she was monitored over a series of classes for her teaching style and techniques before she was allowed to teach her first solo class at WeBarre in June.

Juggling two jobs has made her more conscious about time management.

She says: "Having a side hustle makes you more likely to choose a full-time job you are equally passionate about - because with a back-up plan, your full-time job is a choice, not a necessity."

And though she says that the "comfortable amount" of extra cash she gets from teaching helps with her monthly expenses, she says it is the rapport she shares with her students that keeps her going.

"The extra money doesn't hurt, but it's just a nice bonus," she says. "I'm in it for the positive vibes."

Former lawyer finds new yoga career more relaxed and fulfilling

When Melissa Wong dislocated her shoulder after a nasty tumble during a family snowboarding trip in 2013, she was dismayed to learn that the only cure offered by doctors was surgery.

The doctor suggested a $10,000 operation, but she was against such an invasive procedure.

Looking into alternative ways of healing her injury, the 29-year-old lawyer found yoga. She signed up with local yoga studio Yoga Movement and went for classes four times a week.

Over time, besides increasing the range of movement of her shoulder, yoga also became a solace from her long hours as a litigator.

In 2015, two years into practising yoga as a student, Ms Wong found herself at a crossroads. She was feeling burnt out at work, felt she was plateauing in her yoga practice and wanted to learn more about the spiritual and cultural aspects of yoga.

To challenge herself, she signed up for a $3,600, 200-hour teachertraining course, which ran every weekend over 12 weeks.

During each seven-hour session, she was taught poses, techniques and safety skills as well as about human anatomy and yoga principles. She also spent another $2,500 on a 10-day yoga retreat to Kerala and Mysore in India.

"It was a huge commitment of time and money, but I have no regrets," she says. "Even when I had to work over the weekend, I would just go into the office after 3pm when my classes ended. It was very challenging, but I really had my mind set on completing the course."

She passed her theory and physical examinations in October 2015 and took one-to-one teaching assignments to build her confidence.

This year, following a six-month sabbatical from last November - during which Ms Wong quit her job and travelled across New Zealand - she finally took a full-time teaching position at Yoga Movement.

The singleton teaches 15 to 18 classes weekly. Although she now earns a third of what she used to as a lawyer, she says the pay cut is a small price to pay for how much more relaxed and fulfilled she feels in her new career.

"I think more young people are realising that they want to be happy with what they are doing in life," she says.

Trading suits for sweats

On weekdays, he is the well-dressed deputy fashion editor of L'Officiel, planning photo shoots and writing about luxury watches for the magazine.

On weekends, he is sweating it out in singlets and shorts with about 30 people in a Fitness First gym, enthusiastically yelling out steps and instructions.

That is the interesting double life that 27-year-old Kenny Loh leads, juggling a busy job in journalism with being a fitness instructor for the past two years.

The bachelor teaches a Les Mills Body Attack class, which comprises cardio-focused movements such as jumping jacks, lunges and push- ups. Les Mills is a New Zealand company that provides choreographed exercise-to-music group fitness classes to health clubs.

This was the class that he had become hooked on in 2014, when he signed up for a membership at the Fitness First gym opposite his office.

Mr Loh was not a sedentary person at the time. He would go on recreational runs six days a week, clocking 10 to 21km at a time. But the demands of the magazine job were eating into his evenings, so he joined a gym to exercise regularly.

He said the group dynamics of the hour-long Body Attack class catered to a gym newbie like him and he became so obsessed, he started to attend sessions up to four times a week.

Six months later, he was so in love with the classes that he signed on for the initial module training to become an instructor.

He paid $600 to attend a two-day programme, where he was taught coaching styles and grilled on technique and safety. Then he had to audition with Fitness First and co-teach for three months as well as send videos of himself teaching to the Les Mills offices in Australia before he was internationally certified. Since then, he has spent another $400 on advanced instructor training.

Now he teaches four classes every weekend at Fitness First and sometimes takes classes on behalf of other instructors before or after office hours on weekdays.

Being "always on the move", Mr Loh says he has learnt to prioritise his time. "I don't waste my weekends on things like partying because I happen to enjoy spending time learning new choreography and being prepared for my classes," he says.

And though he admits the additional cash helps, he is not in it for the money.

"Fitness brings people together. It is a great community to be part of and I enjoy being part of a profession that is also my passion."