Order your mind as if you had come to the very end. Postpone nothing. Balance life's account each day. The greatest flaw in life is that it is always imperfect, and part of it is always postponed.

What this means

Seneca's instruction is to live each day as a complete life, settling its accounts before nightfall and postponing nothing. The deepest flaw he names is the habit of leaving life perpetually unfinished, always deferred to a tomorrow that may not come. To order the mind as if you had reached the end is to stop waiting to begin.