Fr. Louis Jouin, S.J. "Expression Of The Inward Feelings Of Our Soul"

The giving to God that honor, reverence, veneration and service, which we owe Him as our Creator and our last end, is called worship. It may be performed either by internal or external acts, and hence our worship may be internal or external. Yet our external worship, in order to be worthy of God, must necessarily be the outward manifestation or expression of the inward feelings of our soul; otherwise, it would be mere mummery or hypocrisy.

That we owe to God both internal and external worship, is an obvious truth. Worship consists in acts of adoration, prayer, obedience to God's will, and love for Him. Now, the duty of performing these acts flows necessarily from the relations which exist between us and God. God is our Creator and our last end. 

Since He is our Creator, we are bound to acknowledge His infinite power and majesty, and His supreme dominion over us. We are therefore obliged to adore Him. We must acknowledge our entire dependence on Him; hence arises the duty of prayer, and of entire submission to His divine will. We are also bound to thank Him for all.

Link (here) to the mentioned portion of the book entitled, Evidences for Religion by Fr. Louis Jouin, S.J.