When Marieke won four medals at the Paralympics, she'd already been approved for euthanasia.

In 2008, Marieke Vervoort was handed documents that spelled the end of her life. She wasn’t fearful of them; in fact, they brought her a sense of peace. Because those pieces of paper gave her the power to choose when that would come, and how it would come.

This week, 11 years on, she made that choice.

The 40-year-old Belgian athlete died by voluntary euthanasia on Tuesday in the city of Diest, after decades living with an incurable, degenerative muscle disease.

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The wheelchair racing champion was diagnosed at the age of 14. She lived with paralysis in her legs, constant excruciating pain that left her barely able to sleep, that made her scream so loudly she would wake her neighbours. In recent years, she also experienced deteriorating vision and regular epileptic seizures.

Her condition was one that she felt would eventually become unendurable. That the bad days would swallow the good. In 2008, she obtained approval from doctors to access euthanasia.

But still, Marieke focussed on the present.

She threw herself into sport; wheelchair basketball, swimming, triathlons. At the 2012 London Paralympic Games, she won gold in the T52 100m wheelchair race and silver in the 200m. She followed with a 400m silver and 100m bronze in Rio four years later.

It was then, at a press conference, that Marieke announced her plans to retire and, ultimately, end her life.

Marieke won two medals in London, 2012. Image: Getty.

She gave a glimpse into her daily struggles: "I can suffer so much that I lose consciousness because of pain or I can have, for a few minutes, an epileptic attack. So I have to live day by day."

She mentioned how sport became a way to cope: "Sometimes when I'm training, I push all my pain, everything off me, because I'm so angry. Why me? Why does this have to happen to me? Why all this? I want to live, I want to be happy. I don't want to have any pain. I want to enjoy every little moment."

And she shared a message with the world: "I want to inspire people that they have to live day by day and enjoy every little moment. Everybody can have tomorrow a car accident and die or have a heart attack and die, and please, enjoy every little moment. It can be over tomorrow for anybody."

"I hope everybody sees that this is not murder."

Unlike like most people in her position, she had control over when her 'tomorrow' would be.

In most countries around the world, euthanasia remains illegal. In Australia, voluntary assisted death is only permitted in Victoria under strict conditions. Similar laws are currently being debated in Western Australian parliament.

In an interview with CNN in 2016, Marieke said that she hoped the attention generated by her plans would be heard by legislators around the world.

"I think there will be fewer suicides when every country has the law of euthanasia," she said. "I hope everybody sees that this is not murder, but it makes people live longer."

For 24-hour crisis support, please call Lifeline on 13 11 14.