Some more thoughts on gratitude:
Let never day nor night unhallow'd pass, but still remember what the Lord has done.
Gratitude is not only the memory but the homage of the heart- rendered to God for his goodness. ~N.P. Willis
O Lord, who lends me life, lend me a heart replete with thankfulness.~ Shakespeare
A grateful thougt toward heaven is of itself a prayer. ~Lessing