2 Corinthians 4:15-16 For all things are for your sakes, that the abundant grace might through the thanksgiving of many redound to the glory of God. For which cause we faint not; but though our outward man perish, yet the inward man is renewed day by day.
The Lord was there before the valley, He is in the valley, and He will be there after the valley to renew you day by day.
Regardless of how difficult things becomes, God has promised grace sufficient for whatever you face. Trust Him. The Apostle Paul wrote to the Corinthian Saints about being strong in valley.
2 Corinthians 12:9 And he said unto me, My grace is sufficient for thee: for my strength is made perfect in weakness. Most gladly therefore will I rather glory in my infirmities, that the power of Christ may rest upon me.