We need to practice with the motivation of bodhicitta. You must think that you are practicing Dharma not merely for your own benefit, but in order to liberate all beings from samsara. If you lack this basis of altruism, there is no basis for acquiring the qualities of secret mantra practices. The only basis for the qualities of secret mantra is the motivation of bodhicitta. You need to possess this motivation of bodhicitta at the beginning, the end and throughout your practice. If you possess bodhicitta, then loving kindness and compassion will arise automatically.

-- Khenpo Karthar Rinpoche