Because faith is belief put into action, God frequently expects his faithful to take the first step -- the step of faith -- on their own, and then the miracle from heaven occurs.
We have a beautiful example of how men of faith have the courage to take the first step and then let God do the rest in the story of the crossing of the river Jordan by the Israelites under the command of Joshua:
14 And it came to pass, when the people removed from their tents, to pass over Jordan, and the priests bearing the ark of the covenant before the people;
15 And as they that bare the ark were come unto Jordan, and the feet of the priests that bare the ark were dipped in the brim of the water, (for Jordan overfloweth all his banks all the time of harvest,)
16 That the waters which came down from above stood and rose up upon an heap very far from the city Adam, that is beside Zaretan: and those that came down toward the sea of the plain, even the salt sea, failed, and were cut off: and the people passed over right against Jericho.
17 And the priests that bare the ark of the covenant of the LORD stood firm on dry ground in the midst of Jordan, and all the Israelites passed over on dry ground, until all the people were passed clean over Jordan.
The priests had to take the first step out into the treacherous flood waters of the river Jordan on their own faith before God would work the miracle of parting the waters again, as he had done previously at the Red Sea. If they had not taken that first step of faith, the Israelites could not have crossed over.
We are faced with a parallel situation in our walk with God today. God will gladly forgive us and remit our sins and fill us with the Holy Ghost, but we must take that first step of repentance. It is an action that takes faith on our part, if only a little bit of faith, but faith nonetheless.