The second thought that we need to reflect on is impermanence and mortality. Here we recognise that while obtaining a human rebirth is an extremely precious and rare occasion, losing this human rebirth—dying—can easily happen at any time. Dying is inevitable but no one knows when it will happen; the time of our death is completely unpredictable. As a result of this contemplation, we will generate a strong conviction about the need not to waste time and to make the most of this short and precious life by practicing the Dharma.
[~How to Follow the Path of Liberation]