Verses 7-13:  Hear, O my people, and I will speak; O Israel, and I will testify against thee: I am God, even thy God.  I will not reprove thee for thy sacrifices or thy burnt offerings, to have been continually before me.  I will take no bullock out of thy house, nor he goats out of thy folds.  For every beast of the forest is mine, and the cattle upon a thousand hills.  I know all the fowls of the mountains: and the wild beasts of the field are mine.  If I were hungry, I would not tell thee: for the world is mine, and the fulness thereof.
 Will I eat the flesh of bulls, or drink the blood of goats?
The next few verses give a common theme seen throughout the Old Testament. The theme may be observed in verse seven as God speaks to the Israelites. In essence, God says, 'You people claim to be worshiping me, but your heart is not in it You are just going through the motions of worship.' The warning to Christians is similar. It is really easy for one to merely go through the motions of going to church every Sunday and following along with what everyone else is doing but never giving one's heart to true worship in the first place.
Verse 8-13 basically make the point that God has no need of "things". God is not hungry that He actually eats the animal sacrifices the Israelites made in the process of worshiping Him. God does not have need of anything and the psalmist makes that very clear.
If God has no need of anything, why does He want us to getting involved? The short answer is that God chooses to work through people to lead others to Him and help others grow in their faith in Him. God wants to bless our lives and see our lives make a difference for Him. We can't do that by just going through a routine of mere church service. Rather, we must focus every moment on God. The human mind can only focus on one thing for a certain length of time. The point is God wants us to care about our relationship with Him and care enough to get involved somehow or someway in order to make a difference for Him in this world.
After all, the Old Testament system of worshiping God involved the sacrifice of innocent animals. This is why these verses go on and on about how God doesn't need animals. He is interested in a heart that is committed to serving Him.
Most Christians pray for revival in their lands or in their churches. Revival is about more people coming to know God. The problem with revival is that it is a waste of time unless there is first repentance. Instead of praying for revival in our lands, we ought to pray for first for repentance to occur. The idea of repentance is for people to realize their guilt before God and their need to come to Him, "broken" and not desiring to offer Him anything in return for His help. True repentance provides a path for biblical revival.