'Occupation' in the Bible

And I applied my heart to seek and search out by wisdom concerning all that is done under the heavens: this grievous occupation hath God given to the children of men to weary themselves therewith.

For all his days are filled with grief, and his occupation is sorrowful; even at night, his mind does not rest. This too is futile.

There is one alone and without a second; also he hath neither son nor brother: yet is there no end of all his labour, neither is his eye satisfied with riches, and he saith not, For whom then am I labouring, and depriving my soul of good? This also is vanity and a grievous occupation.