From beginningless time up until this moment, we have cared solely for ourselves and worked solely for our own benefit. Every exertion we performed was for our own benefit alone. But by acting in this way, all we have actually accomplished is more and more suffering. So this time, instead of caring for ourselves, we must care for others. As Shantideva said, "All the sufferings that beings experience in this universe arise from caring for oneself, and all the happiness that beings experience in this world arise from caring for others."
Source: H.H. Sakya Trizin
Contributed by: Lee Weingrad