When my daughter was in college, I taught her to carry her keys in a fist with the longest one sticking out between her middle and ring finger. I told her if anyone comes after her, punch them right in the sternum. They'll back off or go down. I then replaced it with a six inch long hard wood dowel attached to a lanyard and told her to do the same thing. Push it into the sternum, neck, temple as hard as you can.
