However much you suffer in the physical, verbal, and mental hardships that you undergo for the sake of accomplishing enlightenment through the Dharma, apply yourself joyfully and enthusiastically without losing interest. Just as it is necessary to employ drastic treatments to reduce the suffering in serious illnesses, one needs enormous courage to stop the battle of cyclic existence and conquer the enemies that are the afflictive emotions.
— A Torch Lighting the Way to Freedom: Complete Instructions on the Preliminary Practices by Dudjom Rinpoche, Jigdrel Yeshe Dorje
The Buddha said that we should completely subdue our minds. Whatever we do, for good or ill, it is our mind that is the true agent. In the very depths of our being, we all desire one thing: we want to be happy. We don’t want to suffer. But because of this—this wanting—the three defilements of craving, aversion, and ignorance arise, and suffering is what we get. It is because of these defilements that we accumulate actions that prevent us from escaping from samsara. So it is important right from the start to see the difference between a good motivation and an evil one. Our own mindfulness should be our teacher. We must examine what is positive and what is negative with mindfulness. If positive thoughts arise, we should go along with them. If nonvirtuous thoughts arise, we should put a stop to them. A virtuous mind is the source of happiness. An unvirtuous mind is the source of pain. It’s as simple as that—as we can see from our own experience. When the Buddha spoke about the hell realms and the pretas, he wasn’t making it up. He was simply talking about how things are.