Think the same way about other periods of history and whole nations. See how many people chased after some worldly goal with everything they had, only to die soon after and return to dust. But especially remember the people you knew in your own lifetime. They got worked up over meaningless things. Meanwhile, they ignored what their own nature required of them — the thing they should have stuck to completely. Here's what you must remember: match your effort to what each task is actually worth. Do this and you won't get worn out and frustrated by spending too much time on small things.
In the like manner consider other periods, both of times and of whole nations, and see how many men, after they had with all their might and main intended and prosecuted some one worldly thing or other did soon after drop away, and were resolved into the elements. But especially thou must call to mind them, whom thou thyself in thy lifetime hast known much distracted about vain things, and in the meantime neglecting to do that, and closely and unseparably (as fully satisfied with it) to adhere unto it, which their own proper constitution did require. And here thou must remember, that thy carriage in every business must be according to the worth and due proportion of it, for so shalt thou not easily be tired out and vexed, if thou shalt not dwell upon small matters longer than is fitting.