Charles Spurgeon:

A farmer stood in his fields and said,

I do not know what will happen to us all.

The wheat will be destroyed if this rain keeps on.

We shall not have any harvest at all unless we have some fine weather.

He walked up and down, wringing his hands, fretting and making his whole household uncomfortable.

And he did not produce one single gleam of sunlight by all his worrying—he could not puff any of the clouds away with all his petulant speech, nor could he stop a drop of rain with all his murmurings.

What is the good of it, then, to keep gnawing at your own heart, when you can get nothing by it? . . . .

In the same sermon Spurgeon offers another illustration:

I have often used the illustration (I do not know a better) of taking a telescope, breathing on it with the hot breath of our anxiety, putting it to our eye and then saying that we cannot see anything but clouds!

Of course we cannot, and we never shall while we breathe upon it.