The suffering of Mashiach is not physical; it is a spiritual, mental agony. As it says in Tehillim, an iron yoke enters into his soul. Every Jew is in some way connected to the light of the Mashiach. We all have aspects of both of the Mashiachs within us, because Adam was the primordial Mashiach and it was his single soul which was split into millions of pieces, and each one of us received a piece. In certain ways we must be part of G-d, and in certain ways we must be separate of Him. Why does the soul have the job it does? Why was it placed into this framework? There are many things we think are unknowable, but really it's a matter of looking at it the right way and asking the correct questions. The world is capable of giving great goodness. Suffering hides much of the goodness, and this is why the redemption is hidden within great suffering.