There is a certain peace that you experience when you get to the point where you can say, "Lord, I'm not gonna worry about that any more. I'm not going to concern myself with how it's gonna happen. I didn't make the promise, You did."
Whenever opportunities to doubt present themselves (which is very often) resist the urge to fuss, complain, whine, question, etc. It's not like God is going to respond to it anyway. But with each moment of doubt that creeps up, speak back to God what He spoke to you. That's all you need. Put the weight of responsibility back on Him where it belongs. He can handle it. You'll die trying.
Sometimes I have said to God, "I was minding my own business and You brought the subject up. It's on You to bring it to pass. Either You said it or You didn't, and everything You have spoken is going to come to pass."
No need for long drawn out prayers crying out for whatever, saying whatever. Say what He said and be done with it.