Pauline, the key is knowing how AND, most importantly, DOING so. The will must be there, especially when you realize that these techniques can cripple (perhaps for life) or even kill someone.

But attackers don't care if they injure or kill you, and you can return the favor.

Also, try out the techniques with a friend (NOT at full power!) so that you know how they work.

Another thing is to rip your fingernails across the guy's forehead -- very rich in nonlethal blood vessels, which can do a nice job of blinding him with his own blood. You do need reasonably long fingernails for that, though.

There are other things that can be done as well -- like reaching back, grabbing a handful of hair, quickly bending at the waist and throwing the assailant over your head. But these take much practice and, hopefully, proper instruction.