Ruven Sharf told me another great analogy that he heard from his Alexander technique teacher, Meir.
In a military bunker there were 10 soldiers, and they were always exhausted because they were almost always on guard around the bunker. A new commander came, and he put a high observation post, so one soldier was in the post, and four around the bunker, and now the other five soldiers could sleep, keeping rotation so everyone was fresh and functional all the time.
We can notice that many people in kumite tend to be too tense all the time. In self defense classes for kids, we teach how to be present and aware without over-tensing. The muscles become overworked, tired, unresponsive, cannot use full rate of contraction/expansion, and injury is more likely.
From my experience, the more sensitive one is, the less tension and effort is needed. In karate lessons for adults, this means learning to anticipate an opponent’s movement, so you can respond naturally without being in constant protective mode.
What we need to do is increase our sensitivity, our awareness of self and surroundings, and be present. In kids karate classes, this starts early—developing intuitive perception allows the body to relax, respond efficiently, and move with full energy when needed. Using our eyes and focusing too hard does not make us more sensitive; it narrows our awareness and disconnects us from the present moment.
How to become more sensitive and increase awareness is a deeper topic, but the method is engrained in our physical training, in the directions we give students during timing drills, and even in the basics.