Genesis 7

And Noah did all that the Lord commanded him. Pairs of all creatures that have the breath of life in them came to Noah and entered the ark. Genesis 7:5,15 NIV

God took care of the details of getting the animals to the ark, while Noah did his part by building it; which was exactly what God asked him to do.  Often we do the opposite: we worry about details that we have no control over, then neglect specific areas like attitudes, relationships, responsibilities, etc. that ARE under our control.  We need to concentrate on and obey what God has given us to do, and leave the rest to Him.