Here in 3rd Nephi 12, the Savior is teaching us how to become more like Him. The "Beatitudes" are like a stairway. Starting at the bottom as a broken and fallen person we change piece by piece and attribute by attribute until we are more like the Savior. Christ finishes this chapter by then commanding us to be perfect! I know, daunting right? But as we come to understand more fully what that word means we can feel more at peace with who we are and our efforts.