Preserve me, O God, for in thee I take refuge. 2 I say to the Lord, “Thou art my Lord; I have no good apart from thee.”[a]
3 As for the saints in the land, they are the noble, in whom is all my delight.
4 Those who choose another god multiply their sorrows;[b] their libations of blood I will not pour out or take their names upon my lips.
5 The Lord is my chosen portion and my cup; thou holdest my lot. 6 The lines have fallen for me in pleasant places; yea, I have a goodly heritage.
7 I bless the Lord who gives me counsel; in the night also my heart instructs me. 8 I keep the Lord always before me; because he is at my right hand, I shall not be moved.
When I younger I asked God to give me a psalm that could be like my own personal psalm. And this was the one I turned to, Psalm 16. I memorized it and repeated it often. Until this day it is on my heart and lips when I need it or think of it. The beautiful thing about memoriztaion is that God's word gets lodged in our hearts. Like a favorite song its words come to mind easily.
This psalm is a beautiful picture of David's trust in the Lord. He realizes that God is "only" refuge and admits, "I have no good apart from thee". The more David realizes who God is, the more he realizes he has no good apart from Him. David rejoices in fellow believers, but realizes that those who worship another god, only multiply the sorrows in their lives.
Importantly David realizes God has chosen him before he could choose God. He says, "The lines have falled in pleasant places for me. Yea I have godly heritage" These were boundary lines given to the different tribes of Israel. David realizes that every thing he has been given is a result of God's gracious purpose. He didn't have control of the family he was born into, and of the fact that he was destined to be a king.
In Matthew 1 we read about the lineage of Jesus. There are 14 generations from Abraham to David, and then 14 generations from David to Jesus. So we can see why David says, "Yea I have godly heritage." Finally David says, "I keep the Lord always before me, because He is at my right hand i will not be moved!"
You can see why Jesus memorized all the psalms and repeated them often in his ministry. I would encourage you to find a psalm that represents your relationship with the Lord. It will be a way of keeping the Lord always before you, and be a constant assurance that with him at your side you shall not be moved!