When you really desire something, that’s the time you are in danger of “putting out your hand to steady the ark from falling”. That is, you have dug a trench for yourself and positioned yourself in it so that you will not hear the voice of God.
Our noble desires though good and ambitious as they be, must not become our god or idol of worship. Instead of obeying God and serving Him, we delight in our grand and noble desires to the point where we are prepared to disobey God just to ensure we fulfill our noble desires. This is why God will not give us the desires of our hearts knowing that our hearts are in the wrong place; we desire His hand more than His face.
God has to work upon our hearts until we get to a position where our priorities are right. That is, we are seeking His face more than His hands (His blessings, etc). As God continues to work upon our hearts, suddenly to our amazement, we discover that we no longer desire those very things we desired strongly before. We have now repositioned ourselves into a neutral position just like a gear of a vehicle positioned into neutral gear. A neutral position is the ideal position for God to intervene into our lives to perform miracles, signs and wonders. Then the very noble desire we had before comes to the fore as God brings it into manifestation in our lives. We receive the desires of our hearts and He is glorified through it.