Text taken from http://web.archive.org/web/20041118095755/open-mind.org/Serenity.htm, which has a story about its various origins.
See also http://www.cptryon.org/prayer/special/serenity.html. This page is so beautiful.
See also WikiPrayer
It is said that this prayer was written by Reinhold Niebuhr. -- RenZai
“Gib mir Gelassenheit, Dinge hinzunehmen, die ich nicht ändern kann, Den Mut, Dinge zu ändern, die ich ändern kann, und die Weisheit, das eine vom andern zu untersheiden.”
The above is said to be an older version which R Niebuhr quoted.
Homer 's version:
God, grant me the apathy to accept the things I cannot change, laziness so I won't change the things that I can, and wisdom to know....Mmm, donuts!
(That's HomerSimpson, not the dead Greek guy...)