First, with regard to training: just as, for example, when a man faces the inevitability of the arrival of an external foe, before his enemy approaches, he will prepare armour, weapons, and arrows, and train in the arts [of warfare], but only don [and apply] these when the enemy [actually] arrives and strikes, so, in this context, the training takes place before the indications of death have arisen. Since one does not know when one will die, training should be undertaken from the present moment…
Excerpt from The Tibetan Book of the Dead