You will receive power from the Holy Spirit

"I have chosen you from the world to go and bear fruit that will last."  (John 15: 16, 19)

"But you will receive power when the holy Spirit comes upon you,g and you will be my witnesses in Jerusalem, throughout Judea and Samaria, and to the ends of the earth.” (Acts 1: 8)

"I will bear a witness to you in the world, O Lord.  I will spread the knowledge of your name among my brothers, alleluia!"  (Psalm 17: 50; 21: 23)