And then there is the expression, "to make up your mind". This means, simply, to decide to do something.If I make up my mind to sell my old car, it means that I have decided to sell my car. Joanne's friend Susan, the child minder, is always dithering. She cannot decide what to do. Should she wear a red jumper or a blue jumper. Should she read a book or watch television. Should she take a bus or walk. She cannot decide. Joanne sometimes says to her, "For goodness sake, make up your mind!" That means, "Stop wasting time - just decide what to do and do it!