What does it mean to be filled with the Spirit? There are two ways in which the Greek term is translated, and each of them contributes to our understanding.
One way in which the term is used was when the wind filled the sails of a ship and blew it along in the right direction. I think we can see the relevance of that imagery for the way the Spirit can empower Christians to proceed quicker in the right direction.
The other way in which the term is translated is with the meaning of ‘control’. For example, Paul writes that Jesus was exalted that he might fill all things; in that example, Paul means that Jesus was exalted in order to be in control of everything (Eph. 4:10).
The combination of these two images of empowering and ruling over is what Paul means by being filled with the Spirit. It is a question of who is in control of my heart, my mind and my life.
We see an example of this in the life of Jesus. After his baptism, he was filled with the Spirit who compelled him to go into the wilderness to face the temptations of the devil. The filling equipped his humanity with power and direction as he stepped forward to fulfil his calling as Messiah (Luke 4:1).
Another example is Barnabas, who is described as a good man who was full of faith and the Holy Spirit (Acts 11:23-24). He gave sacrificially, he was an encourager, he was a wise pastor, and he was a man who realised his limitations when he went and asked Paul to help him in Antioch.
Stephen also was filled with the Spirit, which enabled him to be a faithful witness as well as a person willing to look after feeding of widows (Acts 6:3-5).
Paul’s language concerning being filled with the Spirit is in the form of a command. He is not making a suggestion nor a recommendation; he is giving a command that he expects will be obeyed. Further, Paul uses a plural form, which tells us that this filling is not limited to special Christians; instead it is a duty and a privilege required of all. Again, Paul uses the present tense, so this experience is not a one-off event; rather it is an ongoing, daily, hourly experience.