When you no longer have expectations, the unexpected kindness of others and small acts of consideration become like "sweet manna from heaven." The feeling that rises spontaneously within one's heart at such times is true gratitude. When one is accustomed to kindness, one can lose the feeling of gratitude. One must constantly return oneself to the spiritual starting point of no expectations.
People have always wondered at the saints, that they are able to walk around serene, whatever happens. But that is because they can choose where they'll be. They don't have to be angry. You see the difference between having scattered emotions and having a fully vibrating, controlled emotional body. This body is made from energy created from choice, from the effort involved in making choices. But it is necessary to practice; then something is possible.