(The following is taken from DAVID GUZIK COMMENTARY ON THE BIBLE, Studylight.org)
Therefore, since Christ suffered for us in the flesh, arm yourselves also with the same mind, for he who has suffered in the flesh has ceased from sin, that he no longer should live the rest of his time in the flesh for the lusts of men, but for the will of God.
Since Christ suffered for us in the flesh, arm yourselves also with the same mind: The commitment God calls us to have is nothing isn’t greater than the commitment Jesus had in enduring suffering for our salvation. In the last days, we need to have a commitment to God that will endure through great struggles.
Jesus communicated the same idea when He told us that anyone who would come after Him must take up his cross and follow (Matthew 16:24). Taking up the cross meant that you were committed and not looking back!
Arm yourself with the same mind: Many of us are defeated in our battle against sin because we refuse to sacrifice anything in the battle. We only want victory if it comes easily to us. Jesus called us to have the kind of attitude that would sacrifice in the battle against sin (Matthew 5:29-30).