You need prayer. Prayer is one of God's ordained means for you to do spiritual warfare and sharing the Gospel is definitely spiritual warfare. Another reason to pray is that you can actually influence God with your payers. Hezekiah's prayer made a difference. That is why you, as a Christian, can be an effective witness, because you have influence with God and because you can ask God to save.
Prayer is a vital part of witnessing.
Pray for more people to witness. It is the world of sinners. They are people like you. Jesus wants people to find salvation and enjoy eternal fellowship with Him. He wants you to preach the Gospel.