Acceptance

Two strategies for achieving happiness: one is to change the external environment to meet the needs (or wants) of the organism; the other is to change the internal state of the organism to adapt itself to the environment.  We can either change the world to satisfy our desires or change our desires by adapting to the world.  Both strategies aim at removing the agitation of desires, one by fulfilling them and the other by relinquishing them. 

From Unlimited Mind: The Radical Experiential Psychology of Buddhism

by Andrew Olendzki (2010)

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.

from The Serenity Prayer

by Reinhold Niebuhr (1943)