Once, I read a story in a book, it told about an old man was on the train, he lost one of his shoes on the window, to everyone’s surprise, he dropped his another shoe out of window quickly. People asked why he was doing that, he said that if the person picked up one of his shoes, it was useless, but a pair of shoes could be valuable. The old man is so general and he has the positive attitude towards life. The positive attitude is very important, when we meet difficulties, we will get over them. If we feel frustrated all the time, then we will not be happy. We can’t change bad things, but we can change our attitude.