Wikipedia on Suffering

Wikipedia under Mortification of the flesh said:

Joy in suffering: sharing in the redemption

Saint Paul speaks of such joy in the Letter to the Colossians: "I rejoice in my sufferings for your sake". He had found a source of joy in overcoming the sense of the uselessness of suffering.
Faith in sharing in the suffering of Christ brings with it the interior certainty that the suffering person "completes what is lacking in Christ's afflictions"; the certainty that in the spiritual dimension of the work of Redemption he is serving, like Christ, the salvation of his brothers and sisters.[citation needed]
He states that it is suffering, more than anything else, which clears the way for the grace which transforms human souls. Suffering, more than anything else, makes present in the history of humanity the powers of the Redemption.

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Wikipedia under Mortification of the flesh said:

Joy in suffering: sharing in the redemption]

The teaching of Benedict XVI
Cardinal Joseph Ratzinger who later became Benedict XVI told Peter Seewald in God and the world:

"When we know that the way of love — this exodus, this going out of oneself — is the true way by which man becomes human, then we also understand that suffering is the process through which we mature. Anyone who has inwardly accepted suffering becomes more mature and more understanding of others, becomes more human. Anyone who has consistently avoided suffering does not understand other people; he becomes hard and selfish. Love itself is a passion, something we endure. In love I experience first a happiness, a general feeling of happiness. Yet, on the other hand, I am taken out of my comfortable tranquility and have to let myself be reshaped. If we say that suffering is the inner side of love, we then also understand by it is so important to learn how to suffer — and why, conversely, the avoidance of suffering renders someone unfit to cope with life."

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