Colossians 3:23 And whatsoever ye do, do it heartily, as to the Lord, and not unto men;
It follows on from:
Colossians 3:17 And whatsoever ye do in word or deed, do all in the name of the Lord Jesus, giving thanks to God and the Father by him.
It means that whatever we do must be done as if we were doing it for the Lord Jesus Christ and on his behalf.
I hope you find this helpful.