This here is a retired racehorse who won at the highest level and is now in training for a new career as a riding horse. As part of "Legends Day" at my local track they invited him to lead down the field for one of the Gr.1 sprint races he won himself as a racehorse. The old fella clearly thought he was back to defend his crown because he charged down to the barriers like a cavalry horse into battle! He came back blowing happily and jig-jogging.
He's currently in training with a business that specialises in retraining racehorses and selling them as riding horses. There are a lot of similar set-ups here in New Zealand, as Thoroughbreds are popular competition horses. We try to give all ex-racehorses (whether fast or slow) a chance to find new homes as part of the welfare focus for the industry.