When Rav Baruch Ber was a young boy, his father slapped him for doing something wrong. As any normal child would do, he cried from the slap. After he started crying, he walked over to his bookshelf and picked up his siddur and started davening Mincha. His father asked him what he was doing. He responded that he was already crying and does not want to waste the tears. Therefore, he will use those tears to pray.