“I gave in, and admitted that God was God.” -C. S. Lewis
God promised Abraham a son in spite of his old age. When Abraham (99 years old) told Sarah (89 years old) what God had said, she laughed, saying, “Shall I indeed bear a child, now that I am old?” (Gen. 18:13) God replied, “Is anything too hard for the Lord?” (vs. 14) As promised, God gave Abraham and Sarah their son, Isaac. The lesson for them is also true for you and me, too: there is nothing too hard for God. If you believe and do everything you naturally can then God can do the supernatural.
Now faith is the substance of things hoped for, the evidence of things not seen (Hebrews 1:1, ESV).