"You shouldn't chase after the past, or place expectations on the future. What is past is left behind. The future is as yet unreached. Whatever phenomenon is present, you clearly see right there, right there. Unvanquished, unshaken, that's how you develop the mind. Doing your duty ardently today, for--who knows?--tomorrow: death. There is no bargaining with Death & his mighty horde. Whoever lives thus ardently, relentlessly both day & night, has truly had an auspicious day: So says the Peaceful Sage."

From Pali Canon