Jesus didn't say, "Whosoever shall speak to God about this mountain." He said we should speak directly to the mountain the desired end result.
From a worldly point of view, that sounds foolish. But 1 Corinthians 1:27 explains that God has chosen the foolish things of the world to confound the wise. It's always going to sound foolish to the world when a Christian talks as if what God has promised is reality, especially when those promises seem to contradict the natural evidence around us. But if you want to keep the enemy defeated, that's the kind of talking you'd better be doing.
The Bible says God Himself talks that way! In Romans 4:17, it says, "[He] calleth those things which be not as though they were." God doesn't wait for circumstances to line up before He speaks. He causes them to line up because He speaks. You can do the same thing if you'll make your words agree with His and speak them out of your mouth by faith.
"But what if nothing happens right away?" you may ask. "What if the circumstances don't immediately change?" When Jesus spoke to the fig tree in Mark 11:14, He didn't go back and check to see if anything had happened to it. No, once He had spoken it, He considered it done.
Follow His example. Let your faith speak. Agree with God's Word!