My horse spooks. A lot. He is 6 years old and has been under saddle for almost 1.5 years. I need some advice on how to calm him down. I sack him out a lot with scary things. Tarps are fine, plastic bags are fine, and anything else I can throw at him when I'm on the ground is fine. It's while I'm riding him that the things that suddenly happen scare the bajeesus out of him. A horse could walk through the door of the arena while we are riding and he could spook. Is there anything I can do to build his confidence, or do I just have to wait it out? I know he's still young and green.