The Serenity Prayer is a prayer known to most of us. It is attributed to American theologian, Reinhold Niebuhr who first used it in a sermon in 1943. Since then, it has been adopted by many organizations and by individuals who seek acceptance of life's trials.
There are slight variations to the prayer but the common is:
God, grant me the serenity to accept the things I cannot change,
The courage to change the things I can,
And wisdom to know the difference.