Do your work as unto the Lord? What does that even mean?

And whatever you do, whether in word or deed, do it all in the name of the Lord Jesus - Colossians 3:17

Whatever you do, work at it with all your heart, as working for the Lord, not for human masters. - Colossians 3:23

But as for you, be strong and do not give up, for your work will be rewarded. - 2 Chronicles 15:7