When I lived in New York and later, in Philadelphia, I often walked down the street with some great composer’s music in my head. I loved changing things around, seeing where I could go with them. For example, taking a sprightly piano melody and imagining it played by a violin (or even a trumpet), slowing down and lengthening each bar, each measure, turning a march into a love song, or a dirge into a thing of happiness, then imagining it played by a whole orchestra in joyous triumph.
Beethoven once said that he needed only three notes in order to develop a new melody. It’s true. Just begin with three notes of equal duration, then extend one of them, then another, then repeat a note, then back and forth, drawing out some notes even more, and voila’! you have your own new melody! It’s fun, and keeps the imaginative power of your mind alive.