Think of the comparison and contrasts referred to in this passage. Christ died for me that I might live for Him. He layed down His life for my sake, and I offer Him my life for His sake. He represented me on the cross and I represent Him as His ambassador. He took my pain and I share in His joy. If I suffer for Him it is nothing to compare with what He suffered for me. He presented His body on the cross to fulfill His Father's perfect will, and I present my body to Him as a living sacrifice that I might fulfill His Father's will.
All of this is to show the beautiful exchange that took place on Calvary. When we think of all that Christ was willing to do for us how can we deny Him our willingness to do all we can for Him?