Sometimes when I'm driving, the auto-pilot system gets confused and throws a fit. If a car in the adjacent lane gets close to the corner of the front bumper, the auto-pilot slams on the brakes. It thinks that the other car has cut in front of me, when in fact it hasn't.
But it's cool, I forgive it; it's only trying to protect me. The problem is that its picture of reality is way off. Well, technically it's only off by a few inches, but it doesn't have the understanding that my brain has that it's perfectly safe for the other car to be where it is.
The mind does the same thing all the time. It convinces us that we shouldn't try something because something really bad might happen. It's only trying to protect us, but it's doing it with a very incorrect picture of reality. It's as if the mind's view of the world is through a fish-eye lens. It thinks you're an inch away from the edge of the cliff when in fact, you're hundreds of feet away, as safe as you've ever been.
If your mind really knew how safe you always are, it wouldn't ever hold you back. It wouldn't make you sweat before giving a talk. It wouldn't make you second guess every word before it comes out of your mouth at a party. It wouldn't let you stay at your crappy job just because of the security. If it really knew how safe you are, it would hold open the door for you as you walked out.