Mel Rudder, who grew up in the affluent '90s with parents who "provided well" for him and his siblings, graduated from his Louisville, Ky., high school in 2001 with complacent optimism about his future.
But during his first week of college at Virginia Tech in Blacksburg, everything changed.
Long before smartphones and iPads, students began screaming in the hallways that the nation was under attack, Rudder said, and he rushed into the dorm lounge to witness the North Tower of the World Trade Center collapse at 10:28 a.m.
His grandmother and aunt, both from Barbados, had worked in the neighborhood. "Miraculously, no one was there that day," he said.
"Being a freshman, I felt like my world had turned upside down," Rudder said. "Nothing traumatic had ever happened in my life. It was all flowers and rainbows. It was a shocker and it made me realize how the real world is."
For Rudder, 28, and his classmates, 9/11 and the political world view that followed came to define their coming of age. Some, like Rudder, joined the military and went to war, but others, like classmate Valerie Szybala, chose to learn Arabic and work for peace.
Szybala took an interest in global affairs while a student at West Potomac High School in Alexandria, Va., after traveling with a youth group to Israel in 2000 before the second intifada.
She went on to graduate school at Stanford University to get a degree in international political studies and later lived in the volatile West Bank. At first, her parents questioned her career choice.
"Both of my grandparents served in World War II," Szybala, 28, said. "My parents aren't the most political people ever and they were more in my face about the fact that they worked their way up from nothing. That I had it so easy."
Her paternal grandfather was a line worker at a General Motors plant in Buffalo, N.Y., and her mother's family had grown up in the projects of New York City.
As an adolescent, Szybala said, "If I had something to rally around I didn't know what it was, or I was too young and not thinking about those kinds of things."
As the 10th anniversary of 9/11 approaches, Osama bin Laden, who ordered the attacks on U.S. civilian targets, has been killed by Navy Seals and a so-called Arab Spring has brought political uprisings across the Middle East.
The tumultuous decade has been marked by two wars, natural disasters in Thailand, New Orleans and Haiti, the election of the nation's first black president and an economic meltdown.
During that time, Rudder and Szybala graduated from college, found careers and forged into adulthood. Though they were not there, their alma mater, Virginia Tech, saw the second worst mass murder at a college when 32 people were killed and 25 others wounded on the campus in 2007.
But on that sparkling blue-sky day in September 2001, the world changed in an instant when they were still teenagers.
Judy Kuriansky, a psychologist who volunteered with the Red Cross, counseling students near ground zero in the aftermath of the attacks, said many teens experienced depression -- "not feeling they had a future."
"They were adolescents at the time," said Kuriansky, who later worked in the 2010 earthquake in Haiti. "They were just stepping into their careers and love lives."
In a study of those affected by the national tragedy, Kuriansky said, many asked themselves, "What is my future going to look like and is there a future? Several of them sensed it was the end of the world?"
Two Teens Come of Age in Decade After 9/11
"In general, the overriding thing most kids were figuring out was, 'What is the purpose of my life, because of such a major disaster at home,'" she said.
That disaster gave some, like Rudder, a purpose in life.
Rudder said he was on a path to join the Army with the Corps of Cadets when he began college in 2001. His father had been drafted and served two tours of duty in Vietnam with the Marines. But after 9/11, his anger turned to "rage."
"I wanted to go into the military but we didn't have a real enemy," he said. "Once we were attacked, we identified the enemy early. It was the rage of the attack and then we had somewhere to direct it.
"It followed me though my training," Rudder said. "If I felt a little weak or too slow, I would think of the rage I felt that day and carried it with me. It opened my eyes. After that day I tried to make myself the best that I could be."
Rudder's first reaction was to drop out of college and enlist immediately to join the October 2001 invasion of Afghanistan, when the United States and Britain launched air strikes after the Taliban refused to hand over bin Laden.
But his parents convinced him to stay and become the first in his family to get a bachelor's degree. He got two, one in political science and the other in sociology.
Rudder's initial disdain for the Muslim student in a college chemistry class who said after the terrorist attacks that, "It's nothing compared to what the U.S. has been doing to Arabs for years," has been tempered, he said.
Today, Rudder is a captain in the Army, stationed in Germany, after a seven-month tour of duty in one of the most dangerous areas of Afghanistan fighting against terrorism to win "hearts and minds."
A platoon leader in the province next to Kandahar, he and 44 soldiers were hit with an improvised explosive device at their command outpost. Six were badly injured as a truck flipped on its roof.
But as Rudder was serving his country, Valerie Szybala was exploring the Middle East. She, too, remembers the effects of of 9/11.
Szybala was reading a Shakespeare assignment on a dorm bunk bed Sept. 11, 2001, when her roommate ran in to say the United States had been "bombed."
"It didn't make sense to me," she said. "This wasn't wartime."
But as she watched the second tower of the World Trade Center go down, she worried about her relatives in New York City. And when the Pentagon was attacked, it hit closer to home. Both her parents were Washington, D.C., lawyers with offices not far from where the third of four hijacked planes hit.
Szybala and others watched the U.S. invasion of Afghanistan. "It was hard to be negative and against it after something so tragic happened to my country," she said. But after the United States declared war on Iraq, "it made no sense to me at the time, or now."
As the months passed, Szybala's plan for a future in international affairs suddenly seemed in jeopardy.
"In the aftermath, I saw it as damaging my future, in a way," she said of 9/11 and the political fallout. "Anti-American sentiment was on the rise when [George W.] Bush got aggressive with his foreign policy. People were dancing in the streets on TV. I thought, damn it, this is going to affect my ability to travel. I knew I wanted to work in the Middle East and I knew it would make it harder for me as an American."
Later, at Stanford University, working on a project with Yale University on civilian casualties in Afghanistan, she began to see "the dirty side of nation building," she said.
And as President Bush banned photos of coffins returning from two wars, Szybala wondered whether Americans had not been "shielded" from those images, would the war have been "more real?"
In 2005, Szybala would encounter terrorism first hand. While backpacking for two months in Southeast Asia, an Islamic extremist group set off a bomb a block away from where she was staying in Indonesia.
But it was a catastrophic tsunami that hit Thailand that propelled her to act. Szybala joined a local relief group and worked for three months. She was there when she saw another natural disaster unfold at home: Hurricane Katrina.
Again, just this year, Szybala witnessed history. She said she was studying Arabic in Syria during April's political uprising, "right up until the day they called out the tanks."
"Ours is the first generation to grow up in a globalized world with open communications," Szybala said. "I grew up with chat rooms and AIM [AOL Instant Messenger]. But I Skyped globally with my friends in Syria. Every day, we had connectedness."
Today, with an economy in shambles, Szybala lives at home, sending out resumes, hoping to work for a think tank, or a consulting firm or possibly a nonprofit that does humanitarian work.
"I care about people suffering," she said. "I always felt very lucky to travel in the developing world. Our parents worked hard to give us access to education. If I could spend my life helping others, I don't have the same opportunities, but it would be a great way to spend a life."
"People in my generation feel the same way," she said.
Both Szybala and Rudder acknowledge the world has changed in a decade since the national tragedy.
"Everything has changed: civilian life, airport security, the stuff that's thrown at you on TV, terrorists in the Middle East," Rudder said. "So much has happened that when what happened in Norway [the shooting of 80 children at a camp], everyone assumed he was an Arab terrorist."
Editor's Note: Szybala just took a job with Chemonics, an international development consulting company that "helps governments, businesses, civil society groups, and communities promote meaningful change so people can live healthier, more productive, and more independent lives."