The Three Principal Aspects of the Path

Buddhas and Bodhisattvas see clearly that our neglect of others, our self-preoccupation and our disregard for the connection between actions and their effects are responsible for all our miseries. The feeling that it doesn't matter what we do as long as we can get away with it kills our chances of liberation and enlightenment. Our selfishness robs us of worldly and supramundane good qualities, leaving us naked and empty-handed. It separates us from happiness now and in the future and fetters us to suffering.
Resolve never again to let yourself be dominated by this mean and selfish way of thinking and do everything in your power to combat it. Your happiness begins the moment you recognize self-cherishing as your chief foe. There are many good reasons why cherishing others makes sense. Shantideva says:
The state of Buddhahood is accomplished
Equally through living beings and Victorious Ones.
What kind of behavior then is it to revere
Victorious Ones but not living beings?
...If we truly want to please Buddhas and Bodhisattvas and all those noble beings in the world whom we admire and whose sole guiding principles are their affection, love and compassion for others, we can do nothing better than to cherish living beings.
--from The The Three Principal Aspects of the Path an oral teaching by Geshe Sonam Rinchen, translated and edited by Ruth Sonam