Imagine your soul. It's a part of you. It has mass. At the point of death, our bodies get 21 grams lighter. The soul physically weighs 21 grams. And yet, this soul stands in the supernatural realm as well. It has senses. It needs to be fed. What does it eat? It eats and lives on the Word of God. When we read, study, and inwardly digest the Bible, our soul is fed. What do we do? We avoid reading and studying the Bible, and our souls atrophy. It's much easier to feed the body, which we can see, than the soul, which we can't.
Our souls wither and die, because we are unwilling to feed them. However, hear what Peter says in Acts 5: "And we are witnesses to these things, and so is the Holy Spirit whom God has given to those who obey him." The Holy Spirit is also in the spiritual, or supernatural, realm. He is God's soul, his spirit, and he is a real part of the Godhead, the trinity, one of the three persons. God's soul speaks directly to our souls.
Our souls are quickened, awakened, when the Holy Spirit speaks directly to them. Our bodies feel the quickening. Our souls cry out, "feed me," and our bodies respond by picking up the Word of God. All of this is initiated by the Holy Spirit. Otherwise, we would have no urge to feed our souls. When we say that the Holy Spirit is living inside us, what we are really saying is that the Holy Spirit is speaking to our soul. Our souls are functioning together. He is waking our souls up, interpreting scripture for us, and generally strengthening the "real" part of us. The body will fail and waste away. It is dust and to dust it shall return, but our souls are the imperishable part of us. They last forever. Do we want shriveled up raisins for souls, or do we want vibrant, healthy ones? The Holy Spirit begins this sanctification process in us.
How do we know that this is happening? Beyond actually picking up the Bible and reading it, feeding our souls, look at the other verses in that Acts passage:
When they had brought them, they had them stand before the council. The high priest questioned them, saying, "We gave you strict orders not to teach in this name, yet here you have filled Jerusalem with your teaching and you are determined to bring this man's blood on us." But Peter and the apostles answered, "We must obey God rather than any human authority. The God of our ancestors raised up Jesus, whom you had killed by hanging him on a tree. God exalted him at his right hand as Leader and Savior that he might give repentance to Israel and forgiveness of sins. And we are witnesses to these things, and so is the Holy Spirit whom God has given to those who obey him." (Acts 5:27-32)
The disciples were told not to teach in Jesus' name, and yet what did the disciples do? They taught in his name. They couldn't help themselves. This is the sign that we are living in the Holy Spirit, that our souls, and therefore our bodies, are obeying the call. We won't be able to help ourselves, we will insist on teaching in Jesus' name.
Another thing we learn from this Acts passage, is that not only did the disciples disobey the authorities and teach, but as they are confronted by those same authorities, they begin teaching the authorities. The second sentence Peter speaks begins the gospel message. Here is another encapsulated version of the gospel that we can share with others.
We won't be able to help ourselves. We just have to get the subject to Jesus, and we will find every opportunity to speak about him to others. His Holy Spirit commands it, and our souls obey. They grow in love through God. They thirst for knowledge of God. They beg for our bodies, our flesh, to give them the only food they can survive on--the Word of God, truth itself, nourishment and sustenance. The soul speaker commands us, we obey, and we grow.