Swami Vivekananda shooting the eggshell

While Swami Vivekananda was in America, some boys were standing on the bridge and trying to shoot eggshells that were floating in the water. They failed almost at every try, Vivekananda who was watching them from a distance went close to them, took the gun and fired twelve times, and every time he fired, he hit the eggshell. The inquisitive boys asked him how he did it? He replied "Whatever you are doing, put your whole mind on it. If you are shooting, your mind should be only on the target. Then you will never miss. If you are learning your lessons, think only of the lesson. In my country boys are taught to do this."