Secondary school teacher Marilyn Cheng was feeling burnt out after four years of working from dawn to dusk.

As one of the teachers in charge of the sailing co-curricular programme, she started some days at 6.30am and finished work at 8pm.

"We had to take the students for training at East Coast Park twice a week. We usually got back to school only at 8pm," said Ms Cheng.

"It took a toll on my mental and physical health."

With little free time and energy, she went for Aikido class only once a week and jogged occasionally.

But a chance recommendation in 2007 by a friend to work at an international school in Ho Chi Minh City, Vietnam, saw her work-life balance improve dramatically.

She joined a kickboxing gym that year and it transformed her life.

In 2009, she switched to an international school in Jakarta, Indonesia, where she took up muay thai.

She enjoyed the martial art so much that she made frequent trips to Chiang Mai, Thailand, to train, even after returning to Singapore to work in 2014.

Her current job as a flexi-adjunct teacher is akin to being a part-time teacher on a contract basis and she does not need to take work home.

So she has more time to train and, in August last year, she won a muay thai competition in Thailand.

Ms Cheng, who is 37 and single, is now able to exercise four to five times a week. She jogs, goes for muay thai training and started attending Brazilian jiu-jitsu classes in February.

She said: "Being a flexi-adjunct teacher, I have a reasonably good income and I still have the time and energy to keep fit."

She hopes she can continue her healthy lifestyle.

"Because of work stress, I needed an outlet. Ironically, I've now become much fitter because of work."