The avid fitness enthusiast has run six marathons and works more than 50 hours a week as a personal fitness trainer.
But Mrs Sam Blakey cannot seem to get rid of her 'mummy tummy'.
The 52-year-old founder of Ooberfit, a fitness company, tells The New Paper about her struggle with the little known condition 'diastasis recti'.
It occurs when the abdominal muscles around the torso split during pregnancy and do not knit back together afterwards, causing the stomach to bulge.
It was the case with Zara Phillips, the 34-year-old granddaughter of the Queen of England.
A recent photo of the Olympic sportswoman, who has an 18-month-old daughter, sparked rumours that she was expecting another child.
Mrs Blakey realised she has this condition only about four months ago.
She says: "I was working with all these ladies with the condition and had never actually checked to see if I had it.
"So I checked and found that after 16 years, I have a 1cm gap!"
Mrs Blakey adds: "Which means at some point it was probably bigger since I'd had four rather large babies.
"I had never heard of the condition when I was pregnant, only when I was training as a PT (personal trainer), so I never knew to check for it."
During her last pregnancy 16 years ago, she even worked out 38 weeks into her pregnancy before her instructor told her to leave the gym.
With four young children to look after, she did not go back to any kind of exercise for more than a year, going up two dress sizes in the process.
When Mrs Blakey finally decided to get fit and lose the baby weight, she set for herself the target of a 10km race. She soon followed that up with a full marathon.
"I probably could have made the condition even worse as running is high impact, but I think my year off gave it time to heal on its own," she says.
"As personal fitness trainers, we must ensure our postnatal clients are doing the right exercises. Going immediately back to what you were doing before having a baby after only six weeks is a bad choice, yet that is what many women are doing."
Mrs Blakey uses her personal experience to ensure that all her postnatal clients are checked for diastasis recti before she tailors a fitness plan for them.
She considers herself lucky that her diastasis closed naturally over time, although she still has the 1cm gap.
"I probably repaired my diastasis recti by default as I left my body alone and did not stress my abdominal muscles," she says.
"For some women, you can literally dive into their tummy, because their diastasis is so wide. This makes them feel sick to even touch it, and they often face surgery."
Postnatal mothers should not be too obsessed about losing all their weight as quickly as possible, she stresses.
"All the publicity must be very hurtful for Zara Phillips, as it would be for any new mum. Some women still do look pregnant with this condition and it can really affect their confidence.
"There's nothing worse than having someone come up and congratulate you on a new pregnancy when you are not having a baby," says Mrs Blakey.
"It's not about how quickly you lose it, it's about how well you look after your body, and that comes with reshaping yourself to what you used to be, or as near to it, within the parameters of good health."
Up to 40 per cent of post-natal women in S'pore have condition
Senior physiotherapist Ms Danielle Barratt, who specialises in Women's Health at Physio Asia Therapy Centre, provides a short guide for women to follow if they want to check for diastasis recti (DR):
Women who are obese, older, have multiple pregnancies and births or have repeated caesarean sections run a higher chance of suffering from diastasis recti condition, says Dr Lubna Ahmad Harharah.
Dr Lubna is a specialist obstetrician and gynaecologist at the Mount Elizabeth Novena Specialist Centre.
The abdominal wall becomes thinned due to stretching, she adds.
"The diastasis recti condition is a condition that affects around 35 to 40 per cent of postnatal women in Singapore.
"It is the separation (diastasis) of the rectus abdominal muscles due to laxity of the abdominal muscles after a delivery," explains Dr Lubna.
This condition can take several weeks to recover and may cause abdominal discomfort and cosmetic issues.
Dr Ann Tan, an obstetrician and gynaecologist at Mount Elizabeth Hospital, says: "To reduce the risk of diastasis and back strain occurring during pregnancy, women should care for their abdominal muscles and core strength."
Dr Tan advises women to practise antenatal Pilates to train their core muscles to lower the risk of diastasis.
1. To check if a woman has a DR, she should adopt the 'crook lying posture' - lying on her back on a solid surface, with her knees bent near 90 degrees and her feet flat on the floor.
2. Place the tips of the fingers approximately 5-6 cm above the belly button, with fingertips facing downwards.
3. The woman should then lift her head off the floor very gently, breathing out as she lifts her head off the floor, she will be able to feel her abdominal muscle contract towards and either side of her fingertips.
4. The distance left where the muscles do not close is the DR gap.
This article was first published on July 19, 2015. Get The New Paper for more stories.