Remember that man lives only in the present, in this fleeting instant; all the rest of his life is either past and gone, or not yet revealed. Short, therefore, is man's life, and narrow is the corner of the earth wherein he dwells.
To-morrow's action! Can that hoary wisdom, Borne down with years, still doat upon tomorrow! That fatal mistress of the young, the lazy, The coward, and the fool, condemn'd to lose A useless life in waiting for to-morrow, To gaze with longing eyes upon to-morrow, Till interposing death destroys the prospect Strange! that this general fraud from day to day Should fill the world with wretches undetected. The soldier, labouring through a winter's march, Still sees to-morrow drest in robes of triumph; Still to the lover's long-expecting arms To-morrow brings the visionary bride. But thou, too old to hear another cheat, Learn, that the present hour alone is man's.
Not to live as if you had endless years ahead of you. Death overshadows you. While you're alive and able—be good.