It's that assurance that enables him to take that step of faith. Second, when Joshua took that great step of faith, God exalted him. He didn't exalt himself, but God exalted him. The leader who exalts himself will be eventually brought low by God. But the leader that humbles himself will be exalted by God.
Faith is a by-product of humility.
Faith grows in a humble heart because a heart of humility depends wholly upon God. Finally, a spiritual leader will unashamedly call the people of God to absolute surrender to the will of God. Joshua knew that God's work must be done God's way. It was not enough to simply step out in faith. Joshua had to lead the people to do the will of God in the way of God.