Good excerpt from the book "First In, Last Out" by John Salka, a New York City fire battalion chief.
Trust comes from consistency. You have to work beforehand to develop it, but even then, what I've discovered is that you don't create trust. Trust comes from your people, not you. When your people see you at the head of the column, being the first one in, facing each danger alongside them, you simply create the conditions that make trust possible. You can't make trust, you can only make trust possible. That's because trust is people's response to you when you act in ways that show them you'll benefit from following your lead.