How do I use groundwork to help a spooky or anxious horse become calmer?

Groundwork is one of the most effective tools for reducing spookiness because it gives you a way to work the horse through fear in a controlled environment where you are not also managing your own safety in the saddle. The goal is not to eliminate the horse's sensitivity — a horse cannot be made un-reactive by force — but to teach it that the handler is a reliable leader whose calm response to a scary thing is the most useful information available. When the horse spooks at something on the ground, your first job is to not react. Hold your position, keep your breathing slow, and wait for the horse to return its attention to you. Then ask it to go back to work — a direction change, a yield, a halt — so its brain has something to do other than fixate on the alarming object. Systematic desensitization on the ground builds a general tolerance for novelty: introduce unusual objects — tarps, plastic bags, flags, umbrellas — at a distance where the horse shows awareness but not panic, then gradually decrease the distance over multiple sessions as the horse habituates. Never flood the horse by forcing it into contact with something that terrifies it — that suppresses the response without building genuine confidence and often makes the underlying anxiety worse. Round pen work that asks the horse to move around a scary object at distance, then gradually spiral closer, is a controlled way to let the horse work through the fear while keeping it moving forward. A horse that moves forward is thinking; a horse that freezes or bolts has left the thinking brain entirely.