Q What's your secret to looking fabulous?
A I make it a priority to exercise, even on busy days. Sometimes, it might be just a 20-minute workout but it is better than nothing.
Exercising regularly helps me maintain a healthy metabolism. I watch what I eat, though the workouts allow me to consume more of what I like without any weight gain.
Q Was there ever a time when you weren't fit and fab?
A Yes, that was after I gave birth to my first daughter in France as my husband and I were based there.
He was posted to work there for four years. As a first-time mother then, I struggled with no help.
However, I realised that my mood and energy levels were much better when I did get some exercise.
This motivated me to keep up with a regular workout regime and I've been at it since, through my three other pregnancies.
Ms Sim enjoys keeping fit. "The only time I had to slow down was when I was recuperating from my C-section to deliver my babies," said the owner of yoga studio Trium Fitness.
Her husband, 39, a fighter pilot with the Republic of Singapore Air Force, is based in the United States. Their four daughters are now aged 11, nine, five and one.
Q How did you keep fit when you were in France?
A In France, where my first two children were born, I did yoga or pilates and circuit training.
I would also run with a tandem stroller for two babies or cycle with a bike trailer with them in tow, on a daily basis.
I was teaching yoga and pilates and continued doing so when I moved there. This was possible as my students would take turns to babysit my kids in class.
Q What's your diet like?
A I always plan for two snacks and three main meals a day as I need the energy for my daily workouts.
For breakfast, I may have oats, muesli with fresh fruit or two eggs with two slices of toast and a cup of coffee.
For lunch or dinner, I may have rice with two vegetable dishes and a protein dish or a chicken sandwich with a piece of fruit and a salad.
My snacks include cut fruit with yogurt, oats, a protein shake with coconut water or a peanut-butter sandwich.
Q What are your indulgences?
A Ice cream, durian, potato chips and chocolate.
Q How do you maintain a healthy work-life balance?
A I make sure I plan holidays, even though that means I have to take the children along.
We usually look for a resort where they can sign up for activities so that my husband and I can relax.
I also keep my weekends free, so that I can spend time outdoors, surrounded by nature, as it has a very calming effect on me.
I also sleep for an average of six to seven hours on most days.
Q What are the three most important things in your life?
A Family, friends and peace.
Q How important is it for you to keep up with your fitness routine?
A It is as important to me as taking a shower and brushing my teeth.
Without a conditioned body, I believe our quality of life will suffer and affect all areas of our life.
Q How extensive is your collection of sports-related paraphernalia?
A I have two floor-to-ceiling display cases at home filled with my medals and trophies. I also have a home gym.
The amount of fitness apparel that I have is often a conversation topic among my friends. I'm fortunate that my husband has given me his closet space to store them. He wears a flight suit most of the time, so he doesn't need an extensive wardrobe.
Q Would you go for plastic surgery?
A Never. I believe in ageing gracefully. I aim to do so through proper exercise and diet, nothing extreme.
Q Do you think you are sexy?
A Yes, I think I am. I take good care of myself and make an effort to look good and feel sexy because it makes me feel happy and more confident. And this resonates with everything I do throughout the day.