They met at the launch of the "Run To Live Great" programme in July ahead of the Great Eastern Women's Run (GEWR) last year.
And Josephine Oei thought she had found a new training buddy after hitting it off with Irene Lee from the outset.
The pair participated in various fringe activities together for over a month, but Oei was shocked when she found out from an article in The Straits Times that Lee was in the midst of a 21/2-year battle with Stage 3 ovarian cancer.
"I was taken aback because she looked as healthy as anyone else. No one could tell she was ill. She simply looked very well and amazingly beautiful," she said.
"I was overwhelmed with sadness because I am sure she must have gone through a lot of difficult times during her treatment."
Despite her initial shock, Oei admired Lee's resilience and bravery.
They began supporting each other and developed closer ties. They kept in touch through Facebook and spoke about positive events like their next activity together.
The school matron of Anglo-Chinese School (Independent) said: "Irene was nursing a lung infection, thus, she could only take part in lighter indoor activities such as yoga and pilates.
"We did the classes together and she was way more flexible than me. Watching her every move next to me made me feel much more encouraged and I wanted to do my best as well."
On race day, participants were greeted by heavy rain.
Jeanie Tok, who also met Lee at one of the fringe activities, said: "It was pouring heavily on race day and it was drizzling when I met Irene for the last time at the bag collection point.
"She had just recovered from her infection but she braved the storm and walked 5km in style with her poncho. She truly lived a life to the fullest without regrets."
After the race, Oei remained in contact with Lee and went to support her at the art exhibition organised by the Singapore Cancer Society in November.
"Irene had picked up painting as part of her healing therapy. Some of her paintings were featured and I went to give Irene my full support. I understand that Irene was due for another course of chemotherapy but due to her lung infection, the doctor was holding back the chemotherapy," said Oei.
Sadly, Lee's condition deteriorated gradually from March and she died on April 20.
This year, Oei and Tok are running the 21.1km event in the GEWR on Nov 3 in her memory.
Oei said: "I am dedicating the run to Irene to remember her. She was a kind, loving and wonderful lady who never failed to carry a smile on her beautiful face all the time.
"I miss her so much; I wish I could run the race with her again this year."
Sign up for the GEWR at greateasternwomensrun.com