Paul knew that he was not the important one in his own ministry. He knew this faith wasn’t about himself:
2 Corinthians 4:5-6 You see, we don’t go around preaching about ourselves. We preach that Jesus Christ is Lord, and we ourselves are your servants for Jesus’ sake. For God, who said, ‘Let there be light in the darkness,’ has made this light shine in our hearts so we could know the glory of God that is seen in the face of Jesus Christ.
Despite the threats to life and limb, Paul kept on preaching because:
2 Corinthians 4:13-14 But just as we have the same spirit of faith that is in accordance with scripture—I believed, and so I spoke—we also believe, and so we speak, because we know that the one who raised the Lord Jesus will raise us also with Jesus, and will bring us with you into his presence.
Some suggest that I believed, and so I spoke refers to Psalm 116:10. It would be appropriate, as the Psalm is giving thanks for deliverance from death:
I believed, therefore I spoke,
I was greatly afflicted;