Ninja had some good points. I figured I would throw out the possiblity that you are experiencing a fear of the unknown as well. Since it is such a new and vast experience and anything could happen, you don't know what will happen. I still, to this day, start to feel fear when I am deep in space or in a deep body of water. I don't know what I may see and it frightens me a bit. Like ninja said, experience is the best remedey. Just keep practicing and keep trying. Little by little, I'm sure you will be able to overcome it.