I tell the kids in my classes that self defense is "how you keep you safe". When most people think of self defense they think of either martial arts, or a concealed carry license, or pepper spray, or some other technique or device designed to disable an attacker. The words "self defense" conjure up thoughts of the best way to release oneself from a headlock, or a bearhug, or a choke hold. Yes, these things are self defense.
These things are self defense in the same sense that open heart surgery is self defense in case of a heart attack.
If I were to have a heart attack, I am glad that there is a such thing as open heart surgery, just as if I am attacked I am glad that I've spent most of my life involved with martial arts.
However,
When it comes to heart attacks, I hope to never have to resort to open heart surgery. To that end, I am practicing self defense. I have cut down on red meat, nearly completely replaced the grains in my diet with 100% whole grains, increased the vegetable and fruit intake in my diet, I exercise daily. All these things are intelligent self defense against a heart attack.
So why don't more martial arts schools consider the same approach to self defense against physical assault? Sure there are some (very rare) unavoidable situations in which one must defend oneself, but true self defense training should encompass much much more than punches and kicks.
How do you keep you safe from physical attack? Hopefully not by waiting until the attack happens. Be kind to people, more kindness in the world will help. Practice anger management. Don't react without thinking first. Avoid situations that are likely to put you in a physical confrontation. Defend yourself with your mind first, (don't get in a fight and I guarantee you won't get hurt in a fight), your legs second (run, run, run), and your fists absolutely last.