You may break your heart, but men will still go on as before. - Marcus Aurelius

An arrow has one motion and the mind another. Even when pausing, even when weighing conclusions, the mind is moving forward, toward its goal. (Hays translation)

Thou mayest foresee... the things which will be. For they will certainly be of like form, and it is not possible that they should deviate from the order of things now: accordingly to have contemplated human life for forty years is the same as to have contemplated it for ten thousand years.

Use these rules then, and trouble thyself about nothing else.