Gratitude.
HH Radhanath Swami: When I was a little boy, my mother taught me a lesson. She always emphasized, more than anything else, the quality of gratitude. She told me, “If you are not grateful for whatever you have, you receive, you can never be happy. Because if you are not grateful, whatever you get, you expect something else, or you expect more, or you think that you deserved it. But when you are humble and grateful, then whatever comes to your life, the apparent fortune and misfortune, you can actually find happiness in that situation. We could actually be able to see the opportunity that there is to grow in that situation.”