Impermanence

 Many times people ask me, "What to do when I feel that my diligence is decreasing?" Apart from remembering impermanence, there is no other good method. It is the best thing to do. Older dharma practitioners need to reflect on impermanence, because it will cause them to perfect their practice. For example, when Milarepa was about to pass away into nirvana, the last song he sang to Rechungpa was about impermanence. It is true that, in the genuine nature of reality, there is no birth and no death, just as taught in the song, "Three Kinds of Confidence in Genuine Reality." Nevertheless, there will always be the appearances of birth, and death in relative reality.

Khenpo Tsultrim Gyamtso Rinpoche's commentary on Milarepa's song Eight Things to Remember, Karme Choling, 2001, P. 15.