The universe is billions of years old and you get a few decades. That’s not depressing. That’s a reason to pay attention.

A short allotment is what makes attention worth spending. If the supply were unlimited, no particular afternoon would be worth noticing, since there would always be an identical one later. The brevity is exactly what loads an ordinary day with any weight at all. Read one way that is grim; read accurately, it is an argument for looking up.

Pick one part of today to actually attend to, chosen in advance. The walk, the meal, ten minutes with somebody in your house. Doing that once a day is the only sensible response to the arithmetic.