Agonising spasms strike Amy-Claire Davies several times a day, and any one of them could kill her.
Born with an unknown genetic condition, she has to take more than 40 pills every day, lives in pain and needs round-the-clock care.
But the 24-year-old, who was not expected to live past childhood, has chosen to dream of a bright future focussing on her family, friends, boyfriend and hobbies.
"Life is amazing," she said.
She says she is part of a "new generation" of people who, despite being expected to die as children, are still alive well into adulthood thanks to medical advances.
"My world is full of love. I love mammy and daddy, and I love our dogs, I love my friends and family and I love bright clothes, films and books and music, I love unicorns, coffee and of course, I love my new boyfriend Blue," she added.
"I have hopes and dreams for an incredible future. All normal stuff - a house, job, family and above all else, happiness and love."
Amy-Claire's brain sends the wrong messages to the rest of her body, and any emotion such as feeling anxious, sad or happy can make her spasm.
She fights for her life every time - struggling for every breath with her heart rate rising to a dangerous level.
Amy-Claire's bowel does not work so she takes four sachets of a laxative every morning, and endures a daily colonic irrigation while singing along to Whigfield's Saturday Night. She has to take the drug fentanyl which would be fatal to most people.
But she enjoys learning guitar, taking dance classes, yoga and the gym. She trained to swim at the London 2012 Paralympics, but ended up being too ill to compete.
Unlike most people in their 20s, Amy-Claire, who is from Swansea, has an end-of-life plan in place detailing exactly how she would like her death to be managed and details such as which songs she would like played at her funeral.
"I'd really like to trade my body in for a new model," she said.
"Constant agony sucks, nausea sucks.
"There's no cure and I literally live my life knowing each day could be my last."
'Prepared for the end'
Amy-Claire, who describes herself as a "miracle baby" as her parents were told they could not have children, was wrongly diagnosed with cerebral palsy as a child.
But when she hit puberty, the spasms began. And at 15, doctors told Amy-Claire and her parents she could die at any time.
"I don't ever remember not being ill," Amy-Claire said.
"My friends were growing up, dating and doing all sorts of cool stuff while I was going to a children's hospice... We prepared for the end."
She spent her teenage years in a whirlwind race to achieve 200 bucket list dreams.
"I'd never expected to grow up, then as I was daring to imagine a future everything changed," she said.
"I'll never forget the day. I was at home just before my 19th birthday. It was the day that I died."
A spasm had made Amy-Claire's heart stop. Her mother and then health workers spent eight hours resuscitating her.
From then on she and her family were terrified it could happen again and Amy-Claire moved to a residential home in Cardiff for 24-hour care.
After initially fixating on how long she had left, she says she accepts "I've got as long as I've got".
"When I have the really painful ones [spasms], literally my brain just goes 'I wanna die'.
"I'll just sit there and my brain just goes over and over and over 'I wanna die'.
"I think the hardest one especially for mum and dad is I'll say sometimes 'why won't you just let me die?'"
Due to her spasms, Amy-Claire has been left with post-traumatic stress disorder, obsessive compulsive disorder, extreme anxiety and says she has been suicidal.
"I just got so tired from the constant battle but through therapy and a lot of love and support I'm battling on," she added.
"I'm a strong woman because I was raised by a strong woman."
For Amy-Claire, being alive is about making the most of every day.
Her condition is incurable, but she chooses to be an optimist and dares to think about the future.
- Amy-Claire's story, The Incurable Optimist, is on BBC One Wales, on Monday 25 February at 22:40 GMT and on BBC iPlayer.