"As ye sow, so shall ye reap!": Is just as true for Christians as the unsaved. The unsaved says: "What goes around, comes around."

Galatians 6:7 NIV
Do not be deceived: God cannot be mocked. A man reaps what he sows. (Written to Believers!)

Valley's are painful, sometimes too long even, but never lose hope. God will keep His Word, it shall NEVER return to Him void.