I see that verse as a re-statement of what Jesus taught.
God is spirit, and those who worship Him must worship in spirit and truth. John 4:24
It is the Spirit who gives life; the flesh profits nothing; the words that I have spoken to you are spirit and are life. John 6:63
The words of Jesus are spirit, and God is worshiped when we subject our behavior to the life-giving words of Jesus. Some versions translate "reasonable service" to include the word "worship" which I think is appropriate.
We can either live our lives serving ourselves, or we can determine to know and do the will of God. It's an either / or proposition because no one can serve two masters.