One of the most important ingredients in self-defense is Critical Distance. Being too close to an adversary (photo 1 on the left) allows the assailant to execute a hand strike, which can be too fast to defend (photo 2, center). However, by simply extending the distance between you and the assailant (photo 3, right) to at least a two-arm length, you create a safety barrier of time, time which allows you to react positively and avoid being struck.
In the Kiado-Ryu system of self-defense, distance is the #1 security. Simply stated, distance equals time, and the greater the distance, the greater the time it takes for either your opponent to strike you or for you to react to his strike. The moral of this story is … keep your distance, at least a two-arm length, and preferably three.