If your horse does spook at something, put his energy to good use. If it’s an object you can ride around, circle your horse as close as you can to it, and every one and half circles, turn him into the object and head off in the new direction. Horses can only think about one thing at a time. Your horse will either be focused on the scary object or on moving his feet and listening to you. Each time you stop the horse and turn into the object, he’ll get closer to it, until eventually, he’s so focused on you and moving his feet, he’s right next to the object. When you can feel that he’s got his attention on you and isn’t worried about the spooky object, then you can let him rest next to it on a loose rein. If he wants to investigate it (smell it, paw at it, etc.) let him.
If you can’t ride around the object, circle in front of it at the trot or canter using the same concept. When you come up to the object, stop your horse, roll back and ride off in the new direction. Each time you stop and roll your horse back, he’ll get closer to the object until eventually he’s right next to it.
If your horse spooks and you can’t tell exactly what it is he’s spooking at, put his feet to work. Using one rein bend him in a series of serpentines. It’s impossible for a horse to use the reactive side of his brain when he’s constantly stopping and redirecting his feet. When he’s focused on you, put him on a loose rein and head back down the trail. Anytime he gets jumpy, put his feet to work. Soon he’ll be so focused on you he won’t have time to find potential objects to spook at.