"Teach me your way, O LORD, and I will walk in your truth; give me an undivided heart, that I may fear your name. I will praise you, O LORD my God, with all my heart; I will glorify your name forever. For great is your love toward me; you have delivered me from the depths of the grave."
The Psalmist requests the Lord to give him an undivided heart so that he can fear his name. In other words, the Psalmist desires to have a heart set completely on the Lord so that he can live a pure life and put the Lord first. With a heart set on the Lord first, a person's life is centered around obeying the Lord and following his will. Since the Lord's love is so great towards his children, we are extremely grateful for Christ's deliverance from sin and know that Christ will always love us (and watch over us). In return, the Psalmist wants to dedicate his life to God.
The Psalmist mentions that he will glorify God with all his heart forever. His "heart" refers to his passions, his hopes and aspirations, and his everyday life responsibilities. The same idea goes for every believer. For myself, my heart is focused on teaching and doing my best to help my students succeed. Over the short period that I've been teaching, I have come to care for each of my students and I desire the very best for them. I want each one to succeed and I want each one to know that I want them to succeed. I know that I am unable to accomplish this great task all by myself. So, at the heart of my life as a teacher, I want God to give me the wisdom and the strength to teach my students so that they can succeed academically and in life in general. At the heart of my life is hope in the Lord that I will also succeed in my goals.