(Written Wednesday morning on the Manhattan-bound L and uptown F subway trains)

NEW YORK – I'm on my daily morning commute from Brooklyn to Manhattan just after hearing the news about a "plausible but unsubstantiated" terror threat to New York City subways, issued by federal authorities. And unless I end up staying out late and grabbing a cab, I will be on the subway again tonight. And every day and night in the foreseeable future, just like everybody else I know.

Because of all the things to be afraid of, terror attacks do not – and cannot — top my list. Cigarettes are obviously more dangerous, and riding the NYC subway is not an act of bravery. Longtime Gothamites say it was once, during the fiscal crisis of the 1970s, but these days it's a relatively cheap, fast and efficient way to get around.

AP

A New York police officer walks down stairs toward a subway platform, in midtown New York on Wednesday. Â

I think about asking my fellow travelers for their take on the federal warning, but I don't want to break the news about a "plausible but unsubstantiated" threat in this light pre-holiday crowd.

It's a totally normal subway scene – a wonderfully diverse amalgamation of folks reading newspapers and paperbacks, taking mid-morning naps, talking smilingly amongst themselves, typing blog posts on their blackberries. Did the hipster girl across the way just smile at me?

As the subway reached 3rd Avenue, we are held "because of an earlier incident," and the gently authoritative robot conductor voice reminds us to use trash receptacles. His female counterpart, the smoothly digital station agent, advises that a Brooklyn-bound train is arriving on the opposite track. The next one is seven minutes behind. And more will undoubtedly arrive after that.

Normal. Seven-plus years after 9/11, and this city runs and runs and runs.

The most fear I've faced recently in New York was last Sunday night, when the empty tables at a fine restaurant made my companions wonder whether we – or anyone – would ever come back. Or rather, if the depressing, vacant chairs would reinforce the despondent market psychology of diners and spiral the joint out of business.

Frankly, I'm more fearful about my parents' retirement situation – they are back in West Michigan – than I am about anything else. New York will take care of itself. 

We'll keep concentrating on our lives, stacking-up on top of each other, living for the next encounter with another talented hard-working transplant from Xenia, Ohio, or Shanghai or Malibu or Islamabad. Proof-positive, at the 14 Street stop, I walk past a mustachioed guy in a guyabera playing a plaintive Cuban guitar.

That's why I'm here – still here – with my friends. And as a buddy from Tel Aviv always reminds me: we haven't been hit again yet!

Now the F-train has arrived, and we're reminded: "Please help us keep the subway system clean and litter-free."

Good news. Al-Qaida hasn't hit us in a while, the MTA hasn't cut service yet, the restaurants are still open, I'll have Thanksgiving in the leafy suburbs with a tribe comprised of San Franciscans, Detroiters, Parisians and who knows who else.

I switch trains without a hitch and head north, "Rockefeller Center next. Rockefeller Center next."

I hop out and buy some smokes from the South Asian lady in the station kiosk. She gives me a "Happy Thanksgiving" with my change, and I give her one right back.

WASHINGTON – America honors its veterans one day of the year, on Nov. 11. Spc. John Tilley and his fellow tomb sentinels honor them every day of the year.

Tilley is one of 24 soldiers who guard the Tomb of the Unknowns at Arlington National Cemetery. They are part of the 3rd Infantry Regiment (The Old Guard), the Army's oldest active infantry unit.

"We are incredibly proud of what we do," he says.

Tilley and the other sentinels guard the tomb every hour of the day, every day of the year.

U.S. Army

One of the sentinels guarding the Tomb of the Unknowns at Arlington National Cemetery.

"Since 1937 we've never left our post, and that's in every type of weather you can imagine," he says.

Even when Hurricane Isabel was bearing down on the area, in 2003, the sentinels stood their ground.

"They gave the option to leave our post, and the sentinels honorably declined," Tilley says.

That was the only time the sentinels were given that choice. They live by their Sentinel Creed, which states in part, "My standard will remain perfection."

Honor in the details
That perfection is reflected in the way they guard the Tomb of the Unknowns. They walk exactly 21 steps, pivot, wait 21 seconds and retrace their 21 steps for as long as two hours at a time.

"Twenty-one is the highest honor that you can give to the military – the 21-gun salute," Tilley explains. "Everything we do here is off the count of 21."

Another example of their perfection is their spotless appearance. The sentinels spend four to six hours each day just shining their shoes between guard walks.

"That's one pair of shoes," Tilley says. "To get a brand new pair of shoes ready to go takes about 40 to 50 hours."

New shoes are sanded down to eliminate their texture and then re-shined. A power sander is used to sand down the soles of the shoes, which also are shined again.

"We shine, shine, shine and sand down the shine, get all the texture out and start shining them back up," Tilley says. "It's just a long, long process."

A somber place
Tilley tells how veterans often come and sit on the steps overlooking the tomb.

U.S. Army

Spc. John Tilley, one of the guards at the Tomb of the Unknowns at Arlington National Cemetery.

"You can tell there's just a very somber mood about them as they watch us, and some even shed tears," he says. "We're very humbled when they come."

Unlike many soldiers, Tilley, who's 26 and single, didn't have a burning desire to be in the military. He grew up in Statesville, N.C., and graduated from Western Carolina University with a degree in history. He spent a year in a seminary before deciding to join the Army in 2006.

"I was young and fit and wanted to serve my country," he says.

Tilley was selected for the Old Guard and volunteered to be a sentinel at the Tomb of the Unknowns.

"We know we are part of something really special," he says.

He hopes one day to go to Officer Candidate School and become either an infantry officer or a helicopter pilot.

"I'm kind of itching to get in the fight overseas," he adds.

Until then, he'll continue as a sentinel at the Tomb of the Unknowns, completing his 1,000th guard walk before leaving on his next assignment in about a year.

VIDEO: Grief unites fallen soldiers' mothers