Age changes priorities by making time less theoretical.

For a long time the future is an abstraction with apparently infinite room in it. Later you can count the summers, and time stops being a concept and becomes a quantity. Everything reorders once you can feel that, usually in the direction of people over accumulation.

You do not need to wait for the arithmetic to hit you. Ask what you would do differently if you took your remaining time as a real number. The answers tend to be simple and to have been available for years.