As a romantic suspense author, I spend a lot of time writing about ladies in peril. And by that token, I have to get them back out of it. So I'm going to use one day a week to talk about self defense and protecting yourself in various ways.
When you are attacked, you will freeze.
This is true no matter your level of skill or experience. If somebody attacks you when you weren't expecting it, your brain will stop for a moment and struggle to figure out what's going on. It's called the OODA loop:
You can get stuck on any one of these, but many people who are completely inexperienced with combat freeze up on Observe or Orient. Remember, your brain isn't working the way it usually does when you're attacked. It's very easy to seize up on "There is a person hitting me" or "Why is this person hitting me?"
Professionals are able to train themselves to go directly from Observe to Act. They see a punch coming at them, and that's their "go" button (something we'll talk about later). But unless you plan on becoming a violence professional of some kind (and unfortunately, even then, it's not an exact science - police officers and martial arts experts who have only ever trained, and never experienced real violence, often freeze up too in a real scenario) the best thing you can do is to be aware that the freeze exists.
Why does that help? Well, most people don't even realize that this will happen to them. That means that they don't have the opportunity to remind themselves, "I'm frozen. I need to act. I need to do something." Don't underestimate how helpful doing anything can be in a fight, particularly against someone who has perceived you as easy prey. Many criminals will back down if you show that you're willing to put up any fight at all. So repeat it to yourself and save it somewhere in the back of your mind: You will freeze. Break the freeze. Do something.