'I was crying down the phone on Christmas Eve'1

Kirby's diagnosis did not mean the end. Instead, it marked the start of a new challenge: a long, difficult journey back to full fitness and health.

"I didn't know what to do with myself. I was agitated, I was so poorly," she said.

"I would be on really strong medication, which I didn't really agree with in the beginning, but I knew it was the only medication I could take. So I was just forcing it."

She leant on support from Chelsea.

"I remember on Christmas Eve [2019] I called our doctor, Francisco, who was incredible during the process, and I called him crying down the phone - I was like, 'I don't know what to do. I am so ill. I am so tired all the time.' I was sleeping 16, 17 hours a day."

Football was almost the last thing on Kirby's mind.

"My thought process wasn't 'I want to feel better to play football', my thought process was 'I want to be better'," she said.

"Even if I can't play football again, even if I can't go for a run again, I don't want to have a dull, achy pain in my chest."

Kirby said her illness was a "real eye-opener" and gave her a new appreciation for life's simple moments as she got better.

"Walking the dogs, that was just so exciting for me," she added.

"To be able to go back on a pitch and be able to play and be able to train and be involved and going through that was a really, really nice moment, but for me the biggest moment was being able to walk my dogs."