NET
13 I decided to carefully and thoroughly examine all that has been accomplished on earth. I concluded: God has given people a burdensome task that keeps them occupied.
Darby
13 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.
KJV
13 And I gave my heart to seek and search out by wisdom concerning all [things] that are done under heaven: this sore travail hath God given to the sons of man to be exercised therewith.