Suffering for Frankl is a kind of spiritual challenge. He quotes Dostoevsky to this effect, who said the following: "There is only one thing I dread: not to be worthy of my sufferings." With him, Frankl hopes to be worthy of his sufferings. What this worthiness meant for Frankl was to be of use to his fellow prisoners and to rely on his inner freedom and abiding love for his wife.
Frankl is very clear about conditions in the camps. The physical and mental hardships he endured were tremendous, but of the two the greatest test was maintaining his sense of humanity. Frankl says that mental strength was far more important for survival in the camps than physical strength; the source of that strength for him was his sense of self, his desire to help his fellow prisoners, and, in particular, his memory and imagination.
Frankl describes how he is sustained by the thought of his wife and by imagining conversations with her. It is through this imagining that he comes to realize the highest purpose of life, which is love, "the ultimate and the highest goal to which man can aspire." Even when incapable of physically enduring one's situation, one can "endure his sufferings in the right way" by contemplation of a loved one. In other words, even when suffering has taken everything else away, one still has the love they bear for their beloved, a feeling that is ennobling and humanizing.