One way or another, suffering is inescapable. And the question that suffering grinds out from our guts, and that sooner or later reaches our (outer or inner) throats, is "WHY?"
The agony of this "why? question" is at the heart of human suffering.
It is a mystery, of course, a great mystery. Perhaps it has something to do with the fact that we who are mere creatures (a creature is a nothing-in-itself) are being transfigured, divinized, given participation in God's infinite life. The endurance of suffering-in-trust is an inescapable element of this destiny as it is realized in a world of sin and death. At its heart is this radical, transformative love that we are called to accept and respond to, that breaks us open so that we can go beyond ourselves and realize the "likeness-to-God" for which we have been created.
We must endure ("he who loses himself...") with trust ("for my sake," says Jesus).
Still, it makes us gasp. It feels like leaping into an abyss. It's unimaginable. How can we possibly "do" this losing of ourselves, this passage through suffering and, ultimately, dying?
What makes it possible for us is the fact that God Himself has already "done it" in history, in a moment that embraces all moments and all human beings and all suffering. "My God, my God, why have you forsaken me?" Jesus cries out, taking all the suffering of all of us sinners as His own. But in the same breath, He says, "Father into your hands I commend my spirit."
The "distance" of "forsakenness" is filled by absolute, self-emptying love. Thus all suffering is transformed into His suffering which is an expression of His love for the Father in the Spirit, and the revelation and communication of the glory of the God who is infinite Gift.
We can grow, therefore, through suffering in union with Him and His suffering.
It isn't even so much that we (by some autonomous act) "offer" or "unite" our sufferings to His. They already are His sufferings, and through them He draws us into union with Himself. We begin by giving ourselves over, surrendering, trusting in Him, begging Him to accomplish the plan of His love in us. The Lord, in accordance with His wisdom, will generate and sustain within us the very freedom by which we cooperate with Him. He will empower us to say the profound "yes" by which our freedom grows into a communion with Him and a sharing in His freedom and love.
This is indeed a great mystery. We should not be surprised that we feel so poor in front of it, that it can seem so strange, so difficult, so psychologically dislocating sometimes. God sees the depths of human hearts, beyond anything we can understand, even with regard to our own.
Let us never be discouraged. The mystery of His mercy is always at work. Trust in Him!