There are some encouraging verses in the Bible about valleys. Verses that testify to the truth that God is a God of the valleys, as well as the hills (1 Kings 20.23).
In Hosea 2.15 God promises to make the valley of Achor (trouble) a door of hope. In Psalm 84 He promises that for those who trust Him, He will make the valley of Bacca (tears) a place of springs. And in Psalm 23 He promises that even when we walk through the valley of the shadow of death, there is no reason to fear, for He is with us.
I'm grateful for verses like these. They give valley-dwellers and valley-walkers hope. They remind us that God is with us, that He is in control, that He sees, that He turns situations around, and that He can bring good from even the most difficult times. And it's a beautiful thing to have such hope. Hope in itself seems to impart life and joy and peace. You see it in the face of a child as they eagerly wait for Christmas, you hear it in the song of the bird that begins singing before the first rays of morning, and even the lambs seem to skip with joy as Spring awakens a new lease of life on earth. Hope in itself is powerful. But my gratefulness extends beyond mere hope that there are such promises. I really have seen something of the truth of these in my own life, and for that, i am even more grateful. To experience something of what you hope for.... to catch a glimpse of it with your very own eyes, is truly incredible. I can testify to that.
But right now, I'm still walking through valleys. So, i'll joyfully remember what I've tasted of God's faithfulness in the past, I'll put my hope in what He promises for the future, and i'll stand firm on the certainty that He who promises will be faithful once more.