To Serve The Lord means to give the Lord what He wants, when He wants it and how He wants it.
I guess I should be more specific if this is to be helpful.
First of all each of us who are Baptized Into Christ is a Son Of God as well as a Servant Of God so that presents a little challenge up front.
When we think about sons we think of inheritance and privilege.
When we think about servants we think about work and drudgery and poverty.
So, how can we be both?
We learn how from our Lord.
The Holy Spirit Father made Himself a Body in Christ Jesus and inhabits that Body. We call Jesus the Son Of God.
Yet, Jesus clearly stated that He can not to be served but to serve and to give Himself a ransom for many.
Jesus said He came to do the will of His Holy Spirit Father. That made Him a servant to His Father.
How did Jesus handle that service from an attitude perspective? Did He serve grudgingly or reluctantly? Did He avoid hard work - unpleasant tasks?
How was Jesus able to the will of His Holy Spirit Father so perfectly without complaint or pushback?
The Word was made flesh and dwelt among us .
So the Spirit Of God ( Holy Spirit Father) made Himself a Body that could serve His purpose in the Physical Realm.
Well, my body was not custom made and prepared for service one might say.
This is why we must submit our bodies as a living sacrifice to the Lord in order to be able to serve Him properly.
But what leads us to become a son and into manifesting as a servant is a desire for our Lord. Those who are drawn to Him because of who He is, what He is and what He does will find JoyAndGladness in Him - in their relationship with Him.
And having and expressing that Joy Of The Lord is the first step in Serving The Lord.