I want to be a RN, but fear is getting in my way.?

I'm a 23 year old male. I've never been a good student in school, but this is something that I really want to do more than anything. I have this huge fear of failing. I want to eventually go into a Pediatric Unit as a Nurse and work with children. How can I overcome this fear? I've seen people whose parents had less than a high school education, yet there children have the brains to be a RN. How does this happen?