Let's imagine for a moment that you see a child reaching for a pot of boiling oil. You know you can't stop the child from severely burning himself, and he will probably die.
But in that instant, you are given the chance to take the pain and scars on yourself. You will not die, but you will spend your life in incredible pain. Would you do it?
Now let's say that you did this, but the child somehow chose to suffer all the pain anyways...to die, even, because he didn't want you to pay for something he did.
Would you still have taken the pain on yourself? As the child, given that you can't stop someone from suffering your pain for you, what will you do? Will you reject His offering, or accept it in humble gratitude and love?
Therefore I command you to repent—repent, lest I smite you by the rod of my mouth, and by my wrath, and by my anger, and your sufferings be sore—how sore you know not, how exquisite you know not, yea, how hard to bear you know not.
For behold, I, God, have suffered these things for all, that they might not suffer if they would repent; But if they would not repent they must suffer even as I; Which suffering caused myself, even God, the greatest of all, to tremble because of pain, and to bleed at every pore, and to suffer both body and spirit—and would that I might not drink the bitter cup, and shrink—
Nevertheless, glory be to the Father, and I partook and finished my preparations unto the children of men.