God has called every Christian to be a witness, not just with words but with our life. We are called to speak the word of the Lord to others, but we are also called to live according to His will. On both accounts, what we say and how we live our lives are to be truthful witnesses unto the Lord.
We are all called to give testimony as to what God has done in our lives. Not everyone is required to be an evangelists, but all Christians are called to testify to the goodness of God. He has placed you where you are in order to be a witness for Jesus, to testify what you have seen and share your experiences so others may know God as well.