We know that the person of the Holy Spirit dwells in the heart of every believer (Romans 8:9); however, every believer does not seem to possess the power of the Spirit. Some live every day just like pagans. They don’t hear God speak to them; they don’t seem to have any spiritual strength; and they have very little power over temptation.
The problem of course is that they have not allowed the Holy Spirit to be in complete control. If we expect to live in the power of the Holy Spirit we must invite Him to dwell in every part of our life. We must give Him the throne of our heart.
There are a few terms in scripture that are descriptive of this concept of giving Him control. In Galatians 5:16-25 there are three terms used: walk by the Spirit, led by the Spirit, and live by the Spirit. From these verses Paul tells us, essentially, that if we live by the Spirit we must choose to walk by the spirit and be led by the Spirit. Also in Ephesians 5:18 Paul states that we are to be filled with the Spirit. Then in Romans 8:6 Paul indicates that we are to have our mind set on the Spirit.
If we analyze these terms we may conclude that all of them mean basically the same thing—they are descriptive of our giving the Holy Spirit control, also of making Christ Lord. And when we do that we will obtain the power of the Holy Spirit. But the process of making Him our Lord can only be accomplished through prayer.
Our prayers should be not so much for getting power, but to ask Him to fill us and control us; then when He has control in us and is made Lord in us, the result will be that He will wield His power in us and through us.
How often do I have to pray for His filling? I ask Him every day, and sometimes two or three times a day. And the reason is that I continue to sin, and when I sin I exalt myself, and thus I continue throughout the day to have a need for humility and for His Lordship.
And so it makes sense that we all must ask Him to refill us after every time we sin. Ask as often as you sin. When you sin, just say, Lord, I’ve sinned. Will you please fill me again?
Now, when He fills us and gives us His power, what kind of power is it, and what should we expect will happen?
According to Ephesians 1:19-20, it is a great and mighty power; it is the same power that raised Jesus from the dead and seated Him at the right hand in the heavenly places!
In Ephesians 3:16-20 we see that it is a power that will strengthen us in our inner man. Note in this prayer of Paul’s the threefold results of this power:
…that He would grant you, according to the riches of His glory, to be strengthened with power through His Spirit in the inner man,  That Christ may dwell in your hearts through faith;  that you, being rooted and grounded in love, may be able to comprehend with all the saints what is the breadth and length and height and depth and to know the love of Christ which surpassed knowledge, and  that you may be filled up to all the fullness of God.
Paul concludes in verse 20 by saying that according to this power of the Holy Spirit that works within us, He will do exceeding abundantly beyond all that we ask or think.
Yes, He will give us more power than we can imagine. He gives us a mighty power to witness (Acts 1:8). He gives us an enduring power to work and to serve in His kingdom. He also gives us the power in the inner man to rest and reflect, and to draw strength from Him as Christ dwells in us and fills us with love and the fullness of God. And it all comes to us through prayer. Prayer is the key that unlocks the door to this great storehouse of power.