I think this is very cool - "Train me O God, to walk straight; then I'll follow your true path. Put me together, one heart and mind, then undivided I'll worship you in joyful fear." Psalm 86:11 MSG
Looking back, I have often failed to "walk straight" because of a divided heart and mind. My heart wanted one thing and my mind wanted something very different. Since we all live simultaneously in both flesh and spirit, life often gets confusing. I think Paul admitted that at Romans 7 and cried out to God in utter frustration.
An undivided heart is a lifelong challenge for the human spirit because each of us is a walking battlefield. More often than not, the flesh wins the battle and we give in to temptations that we surely know will lead us into a dark, blind alley.
David seems to be in that blind alley and he's reaching up to God to help him know how to "walk straight". Seeing light in a dark alley is possible for the heart that finally recognizes it's divided nature and that only God can pull it all together within us. There is a "true path" back into the light.
If we live long enough, I think we reach a spiritual place where the dominance of the flesh is a reality of the past. As I inch my way to seeing John's Revelation vision for myself, my fleshly nature becomes more memory than reality. This is the ministry of the Holy Spirit - to help me inch along God's true path to see the absolute reality of faith. I think this is what David is referring to with the phrase "joyful fear". Getting to that place is done one inch at a time. HALLELUJAH!