I've just started Gretchen Rubin's marvellous book, The Happiness Project.
And this wonderful Thomas Merton quote is from her blog:
“Finally I am coming to the conclusion that my highest ambition is to be what I already am. That I will never fulfill my obligation to surpass myself unless I first accept myself, and if I accept myself fully in the right way, I will already have surpassed myself.”
-- Thomas Merton, Journal, October 2, 1958