Growing a Big People // The Presence and the Power

Have you ever wondered about the significance of the Holy Spirit?  Not as an abstract theological truth to "know" but as a person relevant and essential to your life and the lives of your family and friends?  How does the presence and the power of the Holy Spirit work in us and through us?  What does it mean to be filled by the presence of a person?If God is already everywhere, why do Christians say things like, "Holy Spirit, we welcome you" or ask "God, fill us with your Holy Spirit"?