Why does Dr. MLK, Jr. say it is difficult to "wait"? history

He said it was difficult to wait because with all the racism that was going on that you shouldn't have to want to wait for a change to come. He wanted change. He thought that nobody should get killed for the color of their skin he wanted us colored people to have a place in the world. I must say its changed from back then a lot but there is still more change to come.