As children we can all remember how good it felt to wake up early Christmas morning to see what "Santa" placed underneath the tree. We were in essence "expecting something great"! As a result, our parents stood back in amazement to see the smiles they put on our faces. This is how God feels when we "expect great things" from Him. He's literally sitting on the throne looking for someone to just flat out believe.
What has God spoken to you? Is it something you can do in your own strength? If so, then you've missed God. God will never ask you to accomplish anything that only you can accomplish. His requests are always bigger than ourselves. God will always use the least of them to do great and mighty works on His behalf in the earth. Look at Moses, he stuttered but he led a multitude of stubborn Israelites on a forty year journey. Rahab the harlot was used to hide spies of God and as a result she and her household was saved. Saul while traveling the road to Damascus murdered Christians before he was translated into one himself. These are just examples of God's grace and mercy and His undying desire to use us for His glory.