By accustoming your mind that there is no time to waste when a life of respites and enrichments is so difficult to find, turn from your obsession with the appearances of this life. By thinking over and again about the problems of recurring rebirth and that the laws of behavioral cause and effect are never fallacious, turn from your obsession with the appearances of future lives. When, by accustoming yourself in this way, you never generate, for even an instant, a mind that aspires for the splendors of recurring samsara, and you develop the attitude that day and night always is interested keenly in liberation, at that time, you have generated renunciation.

-- Lama Tsongkhapa