How do you address a horse that has developed bad habits from incorrect training?

Horses that have been incorrectly trained develop compensatory movement patterns, evasions, and resistance behaviors that become deeply ingrained through repetition, and addressing these habits requires a systematic return to foundational work rather than simply trying to correct the specific problem behavior in isolation. A horse that leans on the bit, for example, may have learned to do so because it was never taught to carry itself in self-carriage and has always used the rider's hand for balance. Correcting the leaning without addressing the horse's inability to balance independently will produce temporary improvement at best. The correct approach is to return to the stage of training at which the horse's foundation was incorrectly built and rebuild from there with correct principles. This is often a slower and more frustrating process than the original training because the horse has established neural pathways for the incorrect response that must be gradually replaced by new ones. Patience is essential — attempting to rush through the re-training process because the horse has already been started will produce the same problems that incorrect initial training produced. The trainer must also be honest about whether the original training error was the horse's or their own, because repeating the same training approach that produced the problem will produce the same result. Many horses that are labeled as difficult, resistant, or untrainable are horses that were incorrectly trained at some point and never given the correct foundation that would allow them to understand and comply with what is being asked. Returning to basics with a willingness to rebuild slowly almost always reveals a horse that is far more capable and willing than its problem behaviors suggested.