For seven years, Sydney Collier enjoyed the life of a happy, active child, with caring, supportive parents and siblings. She ran through sprinklers and played with neighborhood friends. And she fell in love with four-legged animals-especially horses. Her mother encouraged her to ride, and Sydney was good at it, finding herself at home in the saddle.

Then a routine eye exam changed everything.

Sydney had the incredibly rare Wyburn-Mason Syndrome, a congenital birth defect that causes arteriovenous malformations where the veins in the brain's arteries don't separate as they should from the capillaries. The resulting "clumps" of veins and arteries have increased blood flow and a high risk of aneurysm, and they tend to affect the brain, eye, and facial structures. Fewer than 100 cases of Wyburn-Mason Syndrome have been reported, according to the National Institute of Health, and its rarity means treatment remains controversial and prognosis uncertain. Most diagnoses in infants have been confirmed by pathologists after death.

Wyburn-Mason began to take an immediate toll on Sydney's body, first with its effect on her vision, and soon severe physical debilitation and excruciating migraines. Over the next eight years, as she and her family tried treatment after treatment, seeking some sort of hope, the only place where Sydney could escape the almost-constant pain for just a little while was on the back of a horse.

During a risky brain surgery in 2009, Sydney suffered a devastating and massive stroke, which inflicted a new level of disability, putting her in a wheelchair. Determined to ride horses again, Sydney entered a rehabilitation center and refused to give up on her goal of one day riding at the high-performance level for the United States. A year later, on a trip with her mother to the World Equestrian Games in Kentucky, Sydney had a chance to watch the sport of Para Dressage, and that moment helped finally turn what seemed an overwhelming tide of loss and suffering. A new goal was born: to become a competitor in the Paralympics, and to do it in partnership with the only thing that brought her peace and happiness-horses.

This is the story of a brave young woman's journey from the doctors' offices to medal podiums, in her words. Anyone looking for a reason to believe that dreams can be realized, regardless of the odds, will find motivation in these pages.