The very most the devil can ever do in a valley experience is to cast a shadow of death, but a shadow is only a form and it has absolutely no substance to it. The only place a shadow could ever have substance is in one's imagination. A shadow has never had any power to kill or to destroy or even to give the truth about a situation. It casts a powerless darkness.
David received this revelation from God when King Saul was seeking to kill him. David had already received God's anointing to reign, but Saul was on the throne. After we are born again, we have an anointing, but many times there is a Saul reigning in our lives long after the anointing of God has come upon us. But in time, just as Saul was killed with the sword in 1 Samuel 31, the thing in our old nature that wanted to reign will be put to death by the sword of God's Word. Then, our anointing will not only be residential, but it will be the provisional manifestation of our kingship of God's Throne.
God has a provision for you in what appears to be a bed of death. He makes you to lie down in green pastures. He does not make you to lie down in trouble or despair. He will never lead you to a place where you can't be fed and have the water of Life. Shadows may make your situation seem death-like, but Christ wants you to rest in green pastures. The Shepherd loves you so much. Enjoy the green pastures of God's personal provision of love for you.