I haven't been on my mountain bike in 2 years because of this stuff. I love being on the trails and I actually don't mind falling. But, I do mind the thought of serious injury. At one point, I got pretty good going downhill, but unless you practice all of the time, it doesn't stick. And I actually don't see how I could ever get my bike over a log.
The most humiliating cycling experience of my life was when I went on a group mountain bike ride. And this was when I was doing it regularly. I just remember a bunch of people yelling at me to "hold my line," and I didn't know what the hell they meant.