“By cultivating in mind that this human life is so hard to find
Yet has no time to spare, preoccupations with this life will cease;
By contemplating repeatedly the truth of karma and samsaric suffering,
Preoccupations with next life will come to cease.”
From The Three Principal Aspects of the Path by Lama Tsongkhapa. Translated by Thubten Jinpa, Ph.D. PDF available from the Institute of Tibetan Classics.