For a while now, I keep getting nervous and scared while riding. Some days I am doing really well and then the next week I'm nervous again. I don't even know what it really is that scares me. Sometimes I think it is the speed of the horse, or the possibility that the horse will spook and I will fall, Sometimes I think it is just the fact that I think I won't be able to control the horse when these things happen. My trainer knows that I'm nervous and she's trying to help me by telling me to do something and she knows nothing will happen. I feel that something will happen so I refuse, and I feel like I am just disappointing her. What should I do to overcome my fear?