Evaluate the horse's current abilities, temperament, and physical condition. Understand their strengths and areas that may need improvement.  

Shift the training regimen to more varied exercises. Introduce groundwork, flatwork, and jumping exercises gradually to help the horse adjust to the horse's requirements.

Racehorses are conditioned for speed, so they may need to build stamina and develop different muscle groups for different disciplines. Consistent, gradual exercise sessions that focus on endurance, flexibility, and strength can help.

Racehorses may be used to the noise and excitement of the track but not necessarily the calmer, more structured environment of a competition. Expose them to different settings, including various sights, sounds, and other horses, to build confidence.

Depending on the which discipline (e.g., showing, jumper, dressage), customize training to include the specific skills, techniques, and movements required for that discipline. 

Building a solid partnership with the rider is crucial. Spend time developing trust and communication, allowing the horse to feel comfortable in this new setting.

Engaging an experienced trainer who has successfully transitioned Thoroughbreds to competition  horses can provide valuable insights and techniques that can help ensure a smoother transition.

Be prepared for setbacks and take the process step-by-step. Every horse is different, and some may require more time to adjust than others. 

Regular veterinary check-ups, teeth and appropriate nutrition should be prioritized to ensure the horse is healthy and fit for the transition.