Romans 12:1
[1]I beseech you therefore, brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service.

It is by the mercies of God that we present our bodies a living sacrifice, holy and acceptable to God. It is not by condemnation. It is not by judgment. It is not by wrath. By the mercies of God, we yield our bodies to Him, just as by His goodness, we repent (turn to right believing).
More often than not, what we hear in our local assemblies is very contrary to the above scripture. We hear messages that sound like it is by the wrath, fearful judgment and condemnation of God that believers will yield their bodies to God. Then we wonder why it is the case that the more people are told to yield their bodies, the more rebellious they get at it. Knowing the mercies of God, no man will ever shy away from drawing near to Him.
Peter and co experienced the mercies of God by Christ Jesus after they had toiled all night with nothing to show for it, but Jesus in few words blessed them with a net-breaking, boat-sinking load of fishes. When He said they shall be fishers of men thereafter, did they yield themselves to Him or not? They did. They forsook their boats and the draught of fishes and followed Him immediately without blinking an eye or thinking twice about it.
Luke 5:1-11
[1]And it came to pass, that, as the people pressed upon him to hear the word of God, he stood by the lake of Gennesaret,
[2]And saw two ships standing by the lake: but the fishermen were gone out of them, and were washing their nets.
[3]And he entered into one of the ships, which was Simon's, and prayed him that he would thrust out a little from the land. And he sat down, and taught the people out of the ship.
[4]Now when he had left speaking, he said unto Simon, Launch out into the deep, and let down your nets for a draught.
[5]And Simon answering said unto him, Master, we have toiled all the night, and have taken nothing: nevertheless at thy word I will let down the net.
[6]And when they had this done, they inclosed a great multitude of fishes: and their net brake.
[7]And they beckoned unto their partners, which were in the other ship, that they should come and help them. And they came, and filled both the ships, so that they began to sink.
[8]When Simon Peter saw it, he fell down at Jesus' knees, saying, Depart from me; for I am a sinful man, O Lord.
[9]For he was astonished, and all that were with him, at the draught of the fishes which they had taken:
[10]And so was also James, and John, the sons of Zebedee, which were partners with Simon. And Jesus said unto Simon, Fear not; from henceforth thou shalt catch men.
[11]And when they had brought their ships to land, they forsook all, and followed him.
The more we hear the mercies of God preached, the more we present our bodies a living sacrifice, holy and acceptable to Him. After all, who yields to someone who is out to get him/her? Who presents his/her body to someone who is mad at him/her and wants to judge him/her? No one!
Romans 12:1 is one that almost all of us are conversant with, but we have not known the message in it. We focus on the part about the presentation of our bodies but diminish the part of God's mercies right there. Yet without the mercies of God, none of us will present our bodies a living sacrifice, holy and acceptable to God. The key right there is "the mercies of God", yet religion has blinded us to it. We do not see what is greater in that verse. God's mercies is actually greater than our bodies put together. The enemy has got our focus on the wrong thing-our bodies, instead of on God's mercies.
Beloved saint, no man can focus on the mercies of God without presenting his body as a living sacrifice, holy and acceptable to God, just as no one can take his/her bath and not be wet. Peter and his companions could not receive the goodness of Jesus Christ demonstrated in that load of fishes and not follow Him.
It is by the mercies of God, not by determination or commitment or self-efforts. It is by the mercies of God that we present our bodies a living sacrifice, holy and acceptable to God and that is how we get to not conform to the world, but are transformed by the renewing of our minds.
Grace always!