When Mok Ying Rong says that her recent national best time in the half marathon came as an "unexpected surprise" to her, she's not exaggerating.
On April 18, more than a week after she clocked 1hr 23min 14sec at the Gyeongju Cherry Blossom Half Marathon's Women's Open category, she heard from friends in the running community that she had bettered the previous mark of 1:23:16, set by Anne Qi Hui in 2012.
The 22-year-old told The Straits Times: "I was a little doubtful and surprised, but also very excited. I checked it and indeed, I had broken it - I never expected I would be a record holder one day."
The younger sister of fellow national marathoner and 2013 SEA Games gold medallist Mok Ying Ren comfortably beat Koreans Bae Jeong Im (1:28:30) and Kim Ae Yang (1:28:50) to win her category.
Yet she said: "If I knew that this timing was going to be a national record, I would have pushed much harder.
"In hindsight, it was quite a waste, I could have done better - perhaps below 1 hr 23min.
"I feel very inspired. It was never part of the aim and I never believed I could do it. I'm just happy to be able to take my passion for running to the highest level."
Joining her brother as the nation's top half marathon runners - he clocked a national best time of 1:07:08 in January - she has now set her sights on the 2018 IAAF World Half Marathon, having failed to qualify for this year's edition in Cardiff last month.
Despite her "pet event" not being contested at the SEA Games and the Olympic Games, Mok said there are no immediate plans to switch her focus to the full marathon.
Her new personal best, an improvement of more than two minutes from her previous PB of 1:25:31, is all the more surprising for the full-time physiotherapist, who has not been able to clock as much mileage as before, since starting her new job in January. In fact, her last race was the CSC Run by the Bay last November.
Aside from waking up early to run before work, she devotes her lunch breaks to strengthening exercises targeting her foot and knee stabilisers, as well as her hip.
And she believes it is the increased focus on improving her biomechanics and running efficiency that has led to the unexpected achievement. She said: "If I can get my muscular system on a par with my aerobic capacity, I can run so much faster... it's exciting."