There are many things in life over which you have no choice. But the greatest activity of life is well within your dominion. You can choose what you think about. You can be the air traffic controller of your mental airport. You occupy the control tower and can direct the mental traffic of your world. Thoughts circle above, coming and going. If one of them lands, it's because you gave it permission. If it leaves, it's because you directed it to do so. You can select your thought pattern.
Max Lucado