The ancient extinct Kadampa school of Tibetan Buddhism (not the NKT, New Kadampa Tradition, which is an unsanctioned "breakaway" school) practiced mindfulness of death. Their motto was:
Base your mind on the Dharma
Base your Dharma on a humble life
Base your humble life on the thought of death
Base your death on an empty, barren hollow.
"The Words of my Perfect Teacher" by Patrul Rinpoche explain this practice in the following way:
While standing up, sitting or lying down, tell yourself: “This is my last act in this world”, and meditate on it with utter conviction. On your way to wherever you might be going, say to yourself: “Maybe I will die there. There is no certainty that I will ever come back.” When you set out on a journey or pause to rest, ask yourself: “Will I die here?” Wherever you are, you should wonder if this might be where you die. At night, when you lie down, ask yourself whether you might die in bed during the night or whether you can be sure that you are going to get up in the morning. When you rise, ask yourself whether you might die sometime during the day, and reflect that there is no certainty at all that you will be going to bed in the evening.
One Kadampa would always turn his bowl upside down when going to bed, and would not cover the hot ashes to last until morning. When asked why, he answered: "I really cannot say if I will wake up tomorrow".
Besides the ongoing mindfulness of death, there is also a formal meditation on death, which involves contemplating three points:
- that we are sure to die,
- that we can not predict time and circumstances of our death,
- that when we die, there is nothing that can help us.