YORK, Pa. (WHTM) — As the nation mourns through ceremonies and public displays, many take on a much more personal challenge to commemorate the country’s great loss.

There’s walking a mile in someone’s shoes, but on 9/11, that doesn’t quite cut it — especially considering the size of the shoes they’re filling.

Where were you the morning the world changed?

“I was in the library doing some work. I looked up and saw the second plane going into the building,” said Timothy McIver, Crunch Fitness York manager.

“Came home from school — didn’t know why I was let out early,” said Trelonni Elliott of Harrisburg.

“Gather around the TV at school and see what was going on on the news because we had heard something tragic went on,” said Antwan Briscoe of Marietta.

Nineteen years later, every step and every floor climbed by first responders on that fateful day is remembered by challengers on a stair-master. They climb 110 floors to commemorate 110 stories of the World Trade Center.

“I know there were many lives lost that day, but there were also many saved because of those valiant people,” Briscoe said.

“It’s a passion of service and helping people. It’s amazing,” Mciver said.

Hundreds of first responders made the ultimate sacrifice, so a little pain isn’t a problem for people who made the climb.

“The fact that I’m this winded after 18 minutes and 75 floors, I can only imagine how they felt,” Briscoe said.

While the view from the top of the stairs can never compare to the towers, each step they take brings them closer to something much higher.

“Thank you for your service, and god bless you,” Elliott said.

“We truly appreciate you and love you, and keep doing what you’re doing,” Briscoe said.

They’ll keep going, too.

“I could have done faster,” Elliott said.

“Ahh, that was good,” McIver said.