Nobody moves mountains unless God wants them moved. When Jesus was talking to his disciples about faith he was talking about it in the context of ministry. Jesus already gave his disciples the power to perform miracles. Jesus wasn't telling believers how to get everything they want from God.

My first wife and I had two stillborn children. She died from kidney disease when she was 30. So I have no illusions that things will automatically turn out right.

Life is difficult. Tragedies can happen. God doesn't guarantee us freedom from trouble. God guarantees that he will be with us no matter what happens.

One of the best examples of faith is this one:

(Mark 1:40-41 NIV) A man with leprosy came to him and begged him on his knees, "If you are willing, you can make me clean." {41} Filled with compassion, Jesus reached out his hand and touched the man. "I am willing," he said. "Be clean!"