Beth Dobbin is so determined to raise awareness of the illness that has decimated her life that she is speaking out, despite knowing it could trigger a brutal deterioration in her health.
Five years ago, she ran for Great Britain at the Tokyo Olympics. Now, at 32, she spends more than 22 hours a day in bed.
"I've done little things like attend a blood test at the doctors and been in bed for months after. So doing this interview, chatting away for 30 minutes, that could have an impact on me in 2027," she says.
"But I felt like it was really important to do that to get the message out."
She now only gets out of bed to eat and use the bathroom.
Dobbin has been diagnosed with ME, or myalgic encephalomyelitis - a chronic, fluctuating disease, causing symptoms such as sleep problems, problems with thinking and memory, pain and severe, persistent fatigue that does not improve with rest, and more.
A conversation, or even something so simple as a light too bright or a sound too loud, can cause a "crash" that lasts 24, 48 hours, or in the worst cases, months on end.
This year, Dobbin has left the house on just five occasions.
"It's life-decimating like I can't even put into words," she says. "I feel like I've lost everything.
"I have still got my family, but I've lost my independence, my health, the ability to work, the ability to exercise."
For Dobbin it all started with back-to-back Covid and glandular fever infections in the winter of 2021-22. She had not been unwell with either, only discovering she had contracted both through retrospective tests.
She had been sleeping a bit more and her running times were slightly down, but nothing that raised alarm. As time went on, she noticed soreness in the glands of her neck and armpits and a general sense of not quite feeling herself.
British Athletics doctors ran tests that gave no answers, so she carried on, assuming it was lingering glandular fever that would eventually pass.
She qualified for that year's World Championships, Commonwealth Games and European Championships in what was an unusually condensed season owing to the backlog from the pandemic.
Her health progressively deteriorated. At the Worlds, she struggled with a painful throat and was waking at unusual times in the night. At the Commonwealths, she was dizzy while running and her body was more sore than normal.
At the Europeans, she false-started after losing all feeling in her legs while in the blocks. She spoke of her "year of hell" in an emotional interview with BBC Sport after that race.
"When the Europeans had finished, I had this huge rest and the symptoms were just piling on. Things were getting worse and worse," Dobbin says. "I was struggling to stand up, I was sleeping loads, in bed all the time.
"After six weeks, I went back to training. I managed three weeks.
"[Doctors] were just really shocked that I still wasn't doing well and I'd had these viruses months ago.
"I think I saw four or five different specialists because the symptoms that I was having, they were across multiple [body] systems. All the specialists said 'this is ME' and we don't want it to be that because there's nothing out there for it."
ME has no known cure or specific treatment, with patients often relying on off-label medication to manage a condition that can cause more than 200 symptoms, including nausea, headaches, poor cognitive function and brain fog.
The condition is also known as chronic fatigue syndrome (CFS), a label Dobbin strongly rejects. As a former athlete who balanced working eight-hour shifts with training before turning professional, she says she has "known fatigue my whole life" and believes the term fails to capture the severity of the illness.
"I wish it was just fatigue, that would be a walk in the park," she says. "It's so much more than that. If I thought of fatigue in my top 20 symptoms it might just make the cut."
Instead, she says, it feels like her entire body "is shutting down; it feels like you are a few days from death".
More than 400,000 people in the UK are thought to have ME, although the true figure could exceed one million, with severity ranging from people able to work or study to those requiring round-the-clock care and tube feeding.
Despite the length of time she spends in bed, Dobbin often feels too unwell to sleep and requires medication to help her do so.
"Even things like sitting up for a prolonged period of time can take it out of me so I prefer to be just propped up in bed, and that doesn't mean I feel fine. It doesn't get rid of my symptoms, but it makes them less hellish."
For Dobbin's parents and sister Faye, who sit close by to her in support during the interview at the family home in Doncaster, the impact is clear.
"I'm just so desperate to help her but I can't because there is nothing. I'd take her anywhere, I'd take her to America if I had to, but there's nothing," says her father Jim, a former footballer who played for Barnsley, Grimsby and Doncaster Rovers.
Mum Jean adds: "You wake up every day and just feel sad. She should be building her life, living her best life.
"Every day you worry about how she's going to be that day. It's a worry about what our future life's going to be like, who's going look after her if we can't look after her.
"There is nothing out there. There is nowhere to go. You go to the GP and there's nowhere for them to send you to. It's really at the back of the queue as far as research, knowledge, expertise, funding."
There is no specialist service for ME within the NHS and Dobbin says she has found herself educating GPs about the condition.
She had to wait 22 months before she got a face-to-face appointment with a private specialist she sourced herself after her British Athletics funding ended.
On Sunday, Dobbin's younger sister Faye will run the Yorkshire Marathon to raise money for ME Research UK.
"You just feel so helpless and we've been saying this for years now, what can we do?" Faye says.
"It feels like [the marathon] is all I can do other than supporting her emotionally.
"It does feel quite like grief in a way. I'm always worried about Beth. She's always on my mind. I'm worried about what kind of day she is having. What if she never improves? What if she gets worse? What if she gets another virus?"
Asked about her future, Dobbin is straight to the point: "It's very bleak, unfortunately.
"The only positive thing really to say is that Covid happened six years ago now and it's like the whole medical community has woken up."
Since the Covid pandemic and the emergence of long Covid, for which there is a significant overlap in symptoms with ME, there has been a surge in attention and increase in research funding for the condition.
She added: "There will be something, I hope, in the future.
"I said I wanted to speak about it. It's not necessarily that I want to discuss it [but] it's raising that awareness. And unfortunately, athletes are believed a lot more than the average person.
"A lot of people that have this illness that I've spoken to have said to me 'I don't get believed, people think I'm lazy'. I've never experienced one person that doesn't believe me and that's because, why would an athlete just suddenly stop after 20 years?
"I've got a slight platform. If this happened to most people they wouldn't be able to speak about it, so I do feel like I've got a bit of a duty to do that."