When you're on top of a hill, it's very easy to see. The blue sky, the fresh air and sunlight are all visable. In a valley it's much harder. You know the sun must be there but sometimes you can't see the light. It's gets frustrating as you stumble along. It's very easy to get discontent. You want to see the sun and sky and breathe in the fresh air.
God wants us to be content in the valley. There are life lessons to be learned in the hard times. Things that you have to experience.
You can't be refined without fire.
God has promised to be there. Psalm 23:4 says, "Yea, though I walk through the valley of the shadow of death: for thou art with me; thy rod and they staff they comfort me."
So if you're in a valley embrace it. Let God work and refine you.
When you get to the top of the mountain, it will be all the more amazing for having gone through the valley.