Q What's your secret to looking fabulous?
A I average eight hours of sleep every night. A good diet is also very important.
I have been running marathons since my army days. I started using the RunSocial fitness app several months ago. It connects with the gym treadmill using my iPad and has videos of scenic running routes around the world.
The app matches the video speed with my actual running speed, so it feels as if I'm physically running along these routes. It is far more motivating to run this way than just staring at a blank wall.
Q Was there ever a time when you weren't fit and fab?
A During my early university days, I was complacent in my diet and exercise regimen. I became slightly overweight. But in my second year, I decided to get back in shape.
Q What is your diet like?
A I have a heavy breakfast - I like the soft-boiled eggs and black coffee at Ya Kun. Lunch is usually a salad with grilled chicken (no skin or fat). Dinner is usually just a soup. I will snack on fruit if I get hungry between meals.
Q What are your indulgences?
A I love ice cream, in particular, Ben & Jerry's Chocolate Therapy. I give myself one cheat-day a month.
Q What do you do to relax and how do you maintain a healthy work-life balance?
A I work about 55 to 60 hours a week in my own start-up firm. I love what I do, so it feels more like a hobby. I have made keeping fit my company philosophy.
We hire a personal trainer for our Singapore-based staff. Most of us have a session once weekly with him at the office gym. This helps to maintain team morale and keep everyone healthy. What is spent on the personal trainer is saved in medical costs, since my staff take very few sick days off.
Q What are the three most important things in your life?
A My fiancee, whom I got engaged to recently. My family and start-up firm are a close second and third.
Q Would you go for plastic surgery?
A No, I like how I look now.
Q Do you think you're sexy?
A As long as my fiancee thinks I am sexy, that's good enough.
Q What are your favourite and least favourite parts of your body?
A I like my biceps. I don't like my legs, as they are too skinny.
Weight : 65kg
Mr Chang runs his own tech start-up, Wondertech, which he co-founded last year. It specialises in data aggregation software, which may involve using the collected data on a certain segment of online users to push more directed content to them on a website.
He has made keeping fit a priority, even though work takes up most of his time. One way he does this is through the RunSocial app, which allows him to go for "runs" with his colleagues, even though they are in Yogyakarta, Indonesia.
A user creates an event on the app, chooses a route and invites his friends to join in.
"As we run in this virtual world, we can see each other's avatars in real time on the iPad," he said. "We're quite a competitive bunch and like to race with one another."
Mr Chang is an only child. His father Eddie, 60, a project manager, plays squash weekly, and his mother Lily, 58, a business owner, does yoga and dancesports like Zumba.
Q What are your must-dos before and after each fitness session?
A Before every session, I stretch or I'll get a muscle cramp. I like to do a proper cool-down, which involves five to 10 minutes of pacing around and doing gentle stretches.
Q How important is it for you to keep up with your fitness routine?
A Very. I will always make time to keep to my fitness schedule.
Q What's the biggest sacrifice you have had to make to get to your current size today?
A During my junior college days, I would eat ice cream every day. However, after my army days, my metabolic rate dropped, so I have had to give up my daily ice cream treat.
Q What do your family and friends say about your active lifestyle?
A Most of them are also active. My parents have started eating better after seeing my healthier diet and have cut down on carbohydrates.