"The Power of Positive Thinking and The Results of Positive Thinking both written by the American psychologist Norman Vincent Peale may be rewarding to read. The municipal library should stock them...He makes the basic point that it is not so much the disability that one suffers from but one's attitude to it." (Nelson Mandela referring to his wife's heart condition)
Nelson Mandela, imprisoned in 1962 for his anti-apartheid stance, wrote a letter to his wife from prison seven years later. He had just found out she was suffering from blackouts, likely related to her heart condition, and recommended that she read the book The Power of Positive Thinking.
I am not surprised that Mandela suggested such a book given that he survived almost 30 years of imprisonment. It would have been easy for the political prisoner to have become bitter and wasted away in jail. It would have been easy for him to give up on his family. It would have been easy for him to give up on his cause.
However, when Mandela was finally released, shortly after the fall of the Berlin Wall, he took up the cause anew. Within four short years, Mandela won a sweeping victory to become South Africa's first black president. While in prison, he had written an autobiography Long Walk to Freedom, which he had published soon after his election. Mandela practised what he preached: his positive thinking had transported him from a prison inmate to the president of his country.
Nelson burned his racial pass in 1960, an action which led to his arrest for "high treason" courtesy https://en.wikipedia.org/wiki/Nelson_Mandela#Arrest_and_Rivonia_trial:_1962.E2.80.9364