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 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.
— Henri J. M. Nouwen, The Dance of Life by Henri J. M. Nouwen, Michael Ford