Along with trust there must be gratitude — the opposite of resentment. Resentment and gratitude cannot coexist, since resentment blocks the perception and experience of life as a gift. My resentment tells me that I don’t receive what I deserve. It always manifests itself in envy.
Gratitude, however, goes beyond the “mine” and “thine” and claims the truth that all of life is a pure gift. In the past I always thought of gratitude as a spontaneous response to the awareness of gifts received, but now I realize that gratitude can also be lived as a discipline. The discipline of gratitude is the explicit effort to acknowledge that all I am and have is given to me as a gift of love, a gift to be celebrated with joy.
Gratitude as a discipline involves a conscious choice. I can choose to be grateful even when my emotions and feelings are still steeped in hurt and resentment. It is amazing how many occasions present themselves in which I can choose gratitude instead of a complaint. I can choose to be grateful when I am criticized, even when my heart still responds in bitterness. I can choose to speak about goodness and beauty, even when my inner eye still looks for someone to accuse or something to call ugly. I can choose to listen to the voices that forgive and to look at the faces that smile, even while I still hear words of revenge and see grimaces of hatred.
— Henri J. M. Nouwen, The Return of the Prodigal Son, p. 85