Think behind
Get behind me, Satan. You are thinking not as God does, but as human beings do. Literally: Go behind me, Satan, because you do not think the thoughts of God, but the thoughts of men.
The Greek ypaghe opìso means "get behind." The verb ypàgo means "I lead, I take under, I carry, I submit, I withdraw, I go away;" the adverb opìso means "after, behind."
Literally Jesus tells Peter: Get away from me, go back to putting yourself behind me, of submitting to me, you are the one who must follow me, not the other way around; it is the only time in the Gospels that Jesus calls someone "Satan." Satan means enemy, opponent, adversary, accuser. Simon Peter's triumphant idea about a victorious Messiah who would never be subjected to persecution, being spitted on, beaten, tortured, humiliated, and to death on the cross is the fruit of a satanic thought, it is the thought of an adversary to God's plan.
In another part of the Gospel (Matthew 4:10), Jesus uses the injunction "ypaghe, satànà" with reference to the devil. In that passage Jesus wants to chase the devil away in no uncertain terms. That is why the imperative form of ypàgo is not followed by an adverb. Instead in Mark 8:33, immediately after the imperative ypaghe there is opìso mu, "behind me," because it is not Jesus' intention to send Peter away, he is not in fact driving him away, Jesus is unable to do that to anyone ever. Jesus is giving Peter directions on where to go, to where his mind should be. He is inspiring him to rediscover the direction of his heart. Jesus is guiding him to where he should go: to the only place where there is direction and life: behind Jesus.
Before Jesus, beyond Jesus, and outside Jesus there is no useful, good, liberating, peaceful, luminous direction. There is direction only in following His footsteps and His words, otherwise there is no direction at all. If our mind is not constantly led back to stay behind Jesus in humility, in forgiveness, in gratitude in God's present moment, it will get lost in all possible directions, in every direction without direction and it will think as human beings do, and not as God does.