According to scripture - Pro 20:27, the spirit of a man is the lamp of The Lord. You see God is spirit - Jn 4:24 and man is made in the image and likeness of God - Gen 1:26. Therefore man is essentially a spirit. Man is a spirit who has a soul and lives in a body. This is why God leads man through the spirit. God seeks to direct man onto the prefect path.
For you to do all that God has called you to do or to become all that God has called you to be you must be led by the spirit. You must be sensitive to the leanings and promptings of the Spirit of God. The word lamp is used in Pro 20:27 to signify illumination and clarity. God shines light onto your path through your spirit to direct you. Friend learn to yield to the directions of God and you will never fail. As long as you remain committed to God's instructions you will have a 100% success rate.