The Belgian Paralympian Marieke Vervoort, who suffers from an incurable degenerative muscle disease, says she will choose euthanasia, but not yet.
The wheelchair racer, who won a silver medal on Saturday in the 400m, said she signed euthanasia papers in 2008.
The Belgian press had reported she might take her life after Rio, but she rejected the speculation at a news conference following her victory.
She said she was "still enjoying every little moment".
"When the moment comes when I have more bad days than good days, then I have my euthanasia papers, but the time is not there yet," she told journalists in Rio.
Euthanasia is legal in Belgium.
The 37-year-old suffers from a degenerative muscle disease that causes constant pain, seizures, paralysis in her legs and leaves her barely able to sleep.
She was just 14 when the diagnosis was made and gradually her life became "a constant battle".
In spite of it, she achieved a distinguished career in wheelchair racing, winning 100m gold and 200m silver in the 2012 London Olympics, and now a silver medal in Rio.
But the punishing training schedule is proving too hard. This was her last Paralympics, she confirmed, making her Rio achievement bitter-sweet.
"It's a feeling of 'Yes, I won a silver medal'", she told the BBC. "But there is also another side to the medal, the side of suffering and of saying goodbye to the sport. Because I love the sport, sport is my life."
The possibility of euthanasia gave her the courage to keep going as long as she has, she says, adding that euthanasia must not be characterised as "murder."
"It gives a feeling of rest to people," she says. "I know when it's enough for me, I have those papers."
What's the law in Belgium?
- Belgium, like the Netherlands and Luxembourg, permits euthanasia
- A patient's suffering must be constant, unbearable and the illness must be serious and incurable
- Since 2014, a terminally ill child in Belgium may also request euthanasia with parental consent but extra assessment is required
- An adult does not have to be terminally ill but must be mentally competent
- A child seeking euthanasia must be terminally ill and mentally competent