Bhagavad Gita · Chapter 13: The Field and the Knower of the Field

Bhagavad Gita 13.8

indriyārtheṣu vairāgyamanahaṅkāra eva ca | janmamṛtyujarāvyādhiduḥkhadoṣānudarśanam ||

dispassion toward the objects of the senses, absence of ego, and a clear view of the suffering and defect in birth, death, old age, and sickness;

Modern context

One of the marks of knowledge is a clear view of birth, death, old age and sickness. These four were also what, in a famous story, moved the young prince Siddhartha to leave his palace and become the Buddha. Seeing them clearly is not morbid. It is the beginning of seriousness about life. A person who has truly looked at mortality is less likely to waste time on trivial things.