An attack launched by surprise will force you to react from an unprepared state, Therefore your self defense reactions must be instinctive and reflexive. Krav Maga training prepares you for just that. Your subconscious mind will turn your instinctive trained responses into immediate action. Instinct assumes control, for example, in deflecting an incoming straight punch with whichever of your hands is best positioned. Alternatively, you might use a body defense by moving your head away from the blow while tucking your chin. The same instincts will condition you to use your front leg to deflect a straight kick targeting your groin. Practicing and repeating techniques will embed them in your consciousness so you can summon them in a moment of need.