Activating the Holy Spirit within

When the Holy Spirit came upon the men and women in the upper room on the day of Pentecost, it filled them all with the power of the Gospel. They went far and wide to preach about a newness of life in Christ. They were willing to die physically for the sake of this new life in Christ. How can I activate this deep power of the Holy Spirit in my life? How can I be filled with the Holy Spirit, and allow Him to work within me?