She said after a series of relapses and months of treatment over the course of last year, she had received a stem cell transplant in December and had been declared cancer-free.
However, just a week later, in early March this year, Ms Knowles was given the "bitter" news the leukaemia had returned.
The hair salon owner, whose "typical weekend" before her diagnosis involved 100-mile bike rides and 15-mile runs, walked 20 miles around Fairhaven Lake on 16 March to raise funds for clinical research at King's College Hospital.
She said she hoped any donations would improve research on AML, a particularly aggressive cancer which, she said, had not seen any "solid advancements" in treatment for 50 years.
"I always thought that relapse would be a real possibility, but obviously, I just didn't expect it to be so soon," she said.
"All I really miss now is going to work and training. That's all I want – just my normal day and my normal routine.
"It might sound odd to some people, but I would just love to take the dog for a run and go to work, more than anything."
With AML, she explained: "Even if there's a speck of it left, it just regrows.
"And what regrows is basically the resistant cells, the ones that have evaded and resisted the previous chemo."
Ms Knowles' consultant at Blackpool Victoria Hospital had given her three options – try to get a transplant despite her relapse, join a clinical trial or "do nothing".
In November, after various unsuccessful trials, Olivia was given a novel Car-T treatment – immunotherapy which genetically modifies a patient's T-cells to attack cancer.
