Jockey George Chaloner was on a path to the top following a big race win in front of 70,000 people at Royal Ascot in 2014.
But two serious falls left him suffering from flashbacks and post-traumatic stress disorder (PTSD), and unable to get back on a horse.
Chaloner was forced to retire at 25. He has told his story as part of the BBC's State of Sport special, focusing on life after sport.
As part of the study, the BBC has found that one in two former sportspeople have had concerns about their mental or emotional wellbeing since retiring.
READ MORE: Falls, flashbacks and the future