It's called acceptable risk, and if you really want to ride you'll figure it out.
I agree with Drum; it's not IF you'll get hurt, but when and how badly. You can do a lot of things to mitigate how badly though, so don't lose hope.
Horseback riding is one of the most dangerous sports out there. Heck, just being around
horses can be dangerous, especially if you're not experienced enough to be able to read them and keep yourself from getting into sketchy situations.
They're very large prey animals with minds of their own, and even the quietest steady-eddie can have a bad day. As long as you realize that, you should be (mostly) fine.