'Miserable' in the Bible

I applied my mind to seek and explore through wisdom all that is done under heaven. God has given people this miserable task to keep them occupied.

There is a person without a companion, without even a son or brother, and though there is no end to all his struggles, his eyes are still not content with riches. “So who am I struggling for,” he asks, “and depriving myself from good?” This too is futile and a miserable task.