Might as well post the full version, which adds context:

God, grant me the serenity to accept the things I cannot change the courage to change the things I can and the wisdom to know the difference.

Living one day at a time, enjoying one moment at a time.

Accepting hardships as the pathway to peace.

Taking, as he did, the sinful world as it is, not as I would have it.

Trusting that he will make all things right if I surrender to His will; that I may be reasonably happy in this life, and supremely happy with Him forever.

—Reinhold Niebuhr, 1892-1971