" When we help someone with genuine concern for her well-being, levels of endorphins, which are associated with euphoric feeling, surge in the brain, a phenomenon referred to as the helper’s high. In studies in which participants were asked to consciously extend compassion to another person, the reward centers of the compassionate brain were activated – the same brain system that lights up when we think of chocolate or another treat...The fulfillment Mother Teresa derived from her selfless service was a by-product, not the goal. Her primary motive was to bring help and solace to the destitute. This is the catch – a happy catch – to compassion: The more we are in it for other people, the more we get out of it ourselves. "

― Thupten Jinpa , A Fearless Heart: How the Courage to Be Compassionate Can Transform Our Lives