Happiness is always short-lived, which is the setting of natural selection. Only if you don't get long-term happiness will you always have the motivation to find happiness, and you will always strive to survive and spread your genes

Happiness is always short-lived, which is the setting of natural selection.

Only if you don't get long-term happiness, you will always have the motivation to find happiness, and you will always strive to survive and spread your genes.

—Robert Wright, "Why Buddhism Is True"