On a side note, the Bible has enough prayer not on the knees to show us that it isn’t required, but it also has enough prayer on the knees to show us that it is a good thing as well.
The Inner Man
Verse 16: That he would grant you, according to the riches of his glory, to be strengthened with might by his Spirit in the inner man; His prayer is that they might be strengthened with might, but according to the riches of his glory in the inner man by the Holy Spirit (1 Corinthians 16:13). So, his desire is that they are continually strengthened abundantly according the working of the Holy Spirit in the inner man (Romans 7:22; 2Corinthians 4:16).
The inner man is said to be the heart, mind, and soul, as compared to the outer man. Just as the outer man needs to be cared for, so does the inner. Albert Barnes said, "the inner man needs a constant supply of grace. Every Christian needs grace given each day to enable him to bear trials, to resist temptation, to discharge his duty, to live a life of faith." I believe this requires action on our part as that it does not come naturally, i.e., Galatians 5:16.
Illustration: An old Indian Chief, of an American Indian tribe, had just come to a new faith in Jesus, because of the regular visits to his tribe by an early American preacher. As the preacher continued to make his visits to the tribe, he continued to instruct the Chief in the workings of his new faith. One day, as the preacher came to visit, he asked the new Believer, "Well, Chief, how's it going?" The Chief replied,.. "... Two Dogs inside, a Small Dog & a Big Dog, always fighting." So, the preacher asked, "Well, which dog is winning?" To which the Chief replied,.. "The one that I feed." Again, we choose which dog we feed every day.
Dwell in Their Hearts by Faith
Verse 17: That Christ may dwell in your hearts by faith; that ye, being rooted and grounded in love, This is a continuous thought from verse 16 implying that if you they did verse 16, Christ would dwell in their hearts by faith and they would be rooted and grounded in love, and be able to...
Verse 18-19: May be able to comprehend with all saints what is the breadth, and length, and depth, and height; And to know the love of Christ, which passeth knowledge, that ye might be filled with all the fulness of God. In other words, it is only then that they would be able to understand (comprehend) with all the saints the breadth, length, depth, and height of the love of Christ. Of course, none of us can attain to that in this life, but it is no reason not to try. After all, it is necessary if we would ever desire to be filled with the fulness of God. That means to be filled to capacity with Jesus. Who wouldn't want that? Well, it doesn't come by osmosis!