You have to do this and that. Be the best that you can be. Seize the day. Be like somebody else. Et cetera.
'Why?', was asked. 'Life is short.', was answered.
Life is short, man is anxious. Man is selfish. Man is discontented. Man is deceived, imprisoned.
There must be one thing worth doing. Only one. The one which exactly fits the span.
It's obvious. Man knows it.