Voluntary suffering can be redemptive. It can give you strength, and inspire others to join.
In order to achieve a larger goal, a person must often struggle to get to it. For example, it takes countless hours of painful practice and training to become a good athlete. But you suffer through that pain because you understand that by accepting that suffering, you are getting closer to your goal.
Nonviolence is never easy. Organizers in the Civil Rights movement understood that nonviolence may mean that they may have to take a beating. But they went through it because they had a larger goal in mind: freedom. And they understood that violence will not get them that goal in any sustained way.
When 650 marchers were beaten by police on the Edmond Pettis Bridge in Selma, Alabama during Bloody Sunday, those images went out over the newswires and awoke the moral conscience of a nation. Soon, people were driving to Selma in droves. Within 2 days, the number had grown to 2,500. And two weeks later, 8,000 marchers began the long walk to Montgomery, the culmination of a campaign that resulted in the Voting Rights Act.
When we are able to remain nonviolent in the face of violence, we paint a very clear picture of who is right and who is wrong. It brings injustice into the forefront for all to see. And that is the sacrifice that those marchers gave.