I got a note this morning from someone which said, "give thanks for who you are and who you are becoming." I liked it because it reveals some sense of the mystery of freedom, habit, virtue, and vice.
Every choice we make is a choice not only to do something, but to become somebody. Acting gently and peacefully makes us more peaceful and gentle. Deciding to be angry or greedy makes us a more angry and greedy person when we come to the next choice.