The leader demonstrates confidence that the challenge can be met, the need resolved, the crisis overcome.
Worry is an intrusion into God's providence.
The only way God could impose peace on the world would be to robotize our wills and rob every human being of the power of choice. He has not chosen to do that. He has given every person a free will.
Attempt something so impossible that unless God is in it, it's doomed to failure.
The leader seeks to communicate his vision to his followers. He captures their attention with his optimistic intuition of possible solutions to their needs. He influences them by the dynamism of his faith.