U.S. Rep. John Lewis was only 23 when he helped plan the historic March on Washington 50 years ago. But the emotional — and sometimes physical — scars he suffered as a young civil rights leader in the early 1960s matured him beyond his years.

“When you have been sitting on a lunch counter stool and someone walk up and spit on you or pour hot water or hot coffee on you, and say you’re committed to nonviolence, you have to grow up,” Lewis, a Georgia Democrat serving his 14th term in Congress, told ABC’S “This Week” program.

“I was 23, but I was an older person. I was an old soul.”

On Wednesday, Lewis and other veterans of the Civil Rights movement will join thousands of other Americans — many not alive during the era — at the Lincoln Memorial to celebrate the 50th anniversary of the famous march led by Martin Luther King Jr.

The event on the National Mall, which the National Park Service says is permitted for 20,000 people, will take place from 11 a.m. to 4 p.m. and is free and open to the public.

President Obama, the nation’s first black president, who was only 2 at the time of the march, will address the crowd, standing on the same steps at the Lincoln Memorial where King delivered his historic “I had a dream” speech. Former Presidents Jimmy Carter and Bill Clinton also are scheduled to speak.

“It’s unbelievable that in such a short time, an African-American, a man of color, will stand where Dr. King and the rest of us stood 50 years ago,” Lewis told Atlanta’s CBS affiliate WGCL. “I wonder sometime whether it’s history and fate just sort of come together.”

While King’s speech was only 16 minutes long, Lewis said it had a monumental impact in helping the nation move away from its ugly segregationist practices.

“It was so moving, so powerful and the people got with them,” said Lewis, who who stood near King as he addressed the crowd estimated at 200,000 to 300,000. “Some were saying ‘Amen’ and some were just yelling and cheering, but he lift them up, and they were inspired to go back to their hometowns and their states and to work for jobs, for freedom, for civil rights.”

King’s legacy can be seen in the disappearance of the once-ubiquitous signs designating “white” and “colored” water coolers and restrooms. Yet while race relations have improved dramatically in the past five decades, Lewis said the country still faces some of the same issues.

“We’ve made a lot of progress, but we must continue to go forward and we must never ever become bitter or hostile, we must continue to walk with peace, love and nonviolence to create a truly multiracial democratic society,” he told the Atlanta TV station.

“Our country is a better country and we are a better people. The signs that I saw before making it to Washington, they’re gone and they will not return, and the only places our children will see those signs will be in a book, in a museum or on a video. So when people say nothing has changed, I say come and walk in my shoes.”

Organizers are calling on groups and individuals worldwide to ring bells at 3 p.m. Eastern Standard Time Wednesday — a half-century to the minute after King delivered his historic address.