Angelo J. Guglielmo Jr., a filmmaker who became a 9/11 volunteer, poses in New York, Wednesday Sept. 2, 2009. Guglielmo joined thousands of volunteers in the recovery and cleanup in the aftermath of Sept. 11. They are now the inspiration for a new way of marking the anniversary of the attacks. (AP Photo/Bebeto Matthews)

Guglielmo had not lost any friends or loved ones in the attacks on the World Trade Center. There was no clear reason why he should have sneaked into the official supply center and put himself to work, two days after the attacks. No obvious explanation how he'd ended up staffing a tent right at ground zero, offering supplies and assistance to those working on the pile.

Now Guglielmo found himself gathering supplies in an unstable building, looking up to see jagged shards of glass hanging precariously above his head. There he was, too busy to pause and too busy to doubt.

It was only much later that he wondered: What was I thinking?

In the days, weeks and months after Sept. 11, great attention was paid to the nearly 3,000 dead in the attacks and to their stricken survivors. And much was made of the professionals who worked hour after hour at ground zero -- the construction workers who dug through the rubble, the firefighters and police officers who haunted the site, searching for their brethren.

The focus was not on people like Angelo Guglielmo, though thousands of volunteers threw themselves into the maelstrom. And this year, they are the inspiration for a new way of marking the anniversary of the attacks.

Congress and President Barack Obama have declared Sept. 11 a national day of service and remembrance. At www.911dayofservice.org, people have posted their plans to volunteer; among them are folks who intend to collect coats and other winter clothing to deliver to a local shelter, help a friend who suffers from muscular sclerosis or pick up trash along a country road.

For the first time, volunteers will read the names of the dead at the memorial observances at the World Trade Center site -- an honor that has previously been reserved mostly for victims' family members and loved ones, as well as first responders.

The day of service was the brainchild of David Paine of Newport Beach, Calif. For Paine, the aftermath of the worst terrorist attack on American soil has taken on an almost nostalgic glow.

There were so many ways that people came together. Across America, people turned out to give 225,000 units of blood in four days. Over at the supply center, Guglielmo and his fellow volunteers would call a local radio station with lists of what was needed -- and seemingly out of nowhere, the items would just appear.

Paine, overwhelmed by the horror of the events and feeling that he must somehow respond, stepped aside from his public relations business and focused his efforts on promoting volunteerism. Ultimately, he sought to prolong the unity and selflessness of the time by starting an organization encouraging people to volunteer in memory of Sept. 11.

"It was a remarkable feeling that a lot of people hoped would be preserved, but somehow wasn't," Paine says.

U.S. philanthropic organizations saw a surge in volunteers following the Sept. 11 attacks. But the number has dropped. In the year after the attacks, 27.6 percent of Americans over the age of 16 volunteered, and that number grew to 28.8 percent the next year, according to the Department of Labor. But only 26.4 percent volunteered in the year ending September 2008.

Paine was all too aware of how selflessness was turning back to selfishness. New York -- so quietly polite after the attacks -- has long since returned to its noisy, careless, barrel-ahead self. One day Paine realized: The cabbies were honking their horns again.

And so he set out on his crusade to restore the good that came from a horrible moment.

What is it that impels people to enlist, body and soul, when a catastrophe unfolds?

The Rev. Mark Morozowich, associate dean for seminary and ministerial programs at the Catholic University of America. says tragedy can often shake people from their complacency.

"This is a calamity that touched the lives of people ... because it speaks to the brokenness that we all experience and feel in life. Things aren't quite the way they should be," he says.

Taking control of one small piece of the picture and changing a person's life for the better can help bring a sense of peace. Ultimately, the giver can feel that "I was able to be part of the larger human family," Morozowich says.

Some of those who gave of themselves in the wake of Sept. 11 were the giving sort already. Angie Kardashian had never had a problem connecting with strangers. She loves to watch a person's eyes when she gives them her seat on the subway, or offers them a ride in her car.

She had become famous in her small California town for her generosity. Every Thanksgiving, she used her Italian restaurant to prepare dinner for hundreds of Marines and their families, stationed nearby.

But this was different, she thought in the days after 9/11. What could she do to help, she asked one of her customers. She didn't expect his answer: "You can cook, can't you?"

She was terrified. Even today, she cries when she remembers the night she stayed up praying for guidance. In the end, she decided to sell the Tustin, Calif., business she'd built for 22 years, and set off for New York to cook for firefighters.

New York seemed intimidating and huge. When she left, she carried letters in her bags from her hometown police department, fire department and chamber of commerce. Her plan was to present them at New York firehouses to prove she wasn't crazy.

What she thought would be a few months of donated cooking became two years. In the process, she moved 14 times. She ran through the profit from the sale of her restaurant and refinanced her house twice -- ultimately bringing herself to the brink of financial ruin.

She traveled from firehouse to firehouse, cooking up meals. Sometimes she would put on a CD of party classics, and she'd get some of the guys dancing the Macarena. She received a note in the mail from a fire chief, thanking her and saying, "I haven't seen the guys have fun and smile like that in a very long time."

In conversation, Kardashian repeats frequently that she's not married and never had kids. This, instead, is how she hopes to make her mark. During her two years in New York, she came to believe she had found her life's purpose.

Now she has taken a job as a flight attendant, but after some health troubles, she isn't sure she'll be able to make her monthly house payments in California. Lately, she's been considering joining the Peace Corps, maybe asking to be stationed in Africa.

Helping, for her, is an addiction, she says. But it's not one she regrets.

And he knows that this is not entirely an altruistic impulse. The experience at ground zero wasn't all selfless for Guglielmo. Yes, he wanted to give. But he was also looking for some way to cope. He couldn't just sit and watch the news keep scrolling by on TV, he says. He couldn't keep doing nothing.

"Activity was the way that we chose to deal with it," he says now. There were others who joined his group: people who drove up in cars with out-of-state license plates; investment bankers with nowhere else to go. For Guglielmo, doing anything else was simply not an option.

He told his bosses at the publishing company where he was a part-time salesman: Either I adjust my schedule to volunteer, or I quit.

"I needed to commemorate the dead in a way that was deeply personal," he says. "Because I didn't know anybody in the towers, I didn't have anybody to show compassion to."

And what does he carry with him from his experience working alongside the rescue and recovery workers? He still remembers seeing a man in a police uniform come to the tent with a wet sleeve -- he had touched a dead body, and he wanted to know, could the fluids make him sick? Another man, a firefighter, arrived with a raised, red welt on his hand from touching a molten beam. A chaplain stopped by after a stairwell was uncovered, on his way to anoint the dead.

Some of it, he says, is still hard to talk about. Realizing that he was keeping himself so busy in the first few weeks that he still wasn't dealing with the pain of the attacks, he went to see a therapist. How come he still hadn't cried?

The therapist advised him to use his film training and put it all on tape -- perhaps it would help him deal with what he was seeing. As it turned out, the documentary he made, "The Heart of Steel," helped him become a full-time filmmaker.

But even now, it's hard to offer a clear accounting of what drove him to work alongside that toxic pile for months. Paine and Kardashian both say they can't quite explain what drew them to this tragedy, when they could have steered clear of it.

And what was Guglielmo thinking?

Truth was, he says, he wasn't. "Once you started, you couldn't stop," he says. "You had to be guided by a compulsive need to help."