The ancient philosophers recognized it.

Lucan wrote: "The very fear of approaching evil has driven many into peril." There are those who believe that the very concentration of thought upon a possible evil will bring to pass the peculiar arrangement of circumstances that makes the evil.

Of this belief I am not competent to speak, but I am fully assured that it is far from helpful to be contemplating the possibility of evil.

In my own life I have found that worrying over evils in anticipation has not prevented their coming, and, on the other hand, that where I have boldly faced the situation, without fear and its attendant worries, the evil has fled.
Hence, whether worries in hand, or worries to come, worries real or worries imaginary, the wise, sane and practical course is to kill them all and thus _Quit Your Worrying_..