He who began a good work in you will bring it to completion. Paul speaks a deep assurance here: what God begins, he finishes. You are not responsible for the completion. He is.
Rest arises when you realize: you do not have to complete the work yourself. God began. God completes. Your part is to let yourself be led and walk along.
Today: he began. He completes. You may trust and participate without the pressure of managing it all alone.