"All of the positive changes that have come have come from people who believed it, kept doing it, kept doing it, kept doing it, until there was change. Do not get discouraged. Believe that you have the power to change things," said Sondra Hassan, who, at 16 years of age, was a volunteer marshal for the historic March on Washington. NPR talks to six marchers from 1963 about what they remember of that day and how they feel 57 years later about Black Lives Matter protests in the wake of George Floyd's death.