Mandela was open to his 'biggest mistake' that he did not make enough effort to address the sexually transferred diseases like HIV and AIDS during his presidency. He later established many nonprofit organizations to raise awareness. He knew what was right and wrong, and did his very best to correct the wrong.
Nelson Rolihlahla Mandela was a revolutionary anti-apartheid leader, freedom fighter and South Africa's first black president. He was in jail for 27 years (1962-1990) for his freedom struggle against the pro-apartheid white government.
The most amazing thing he did was the abolish apartheid, racial segregation based on color—with the underlying idea that white-skinned people were superior to black-skinned people. It led to equal rights for all the citizens of South Africa. His life-long struggle against the pro-apartheid government finally brought enough internal and external pressure on the regime to bring this change and improve the lives of millions of black people. He was awarded hundreds of honors, chief among them the Noble Prize, Order of Lenin and Presidential Medal of Freedom.