Ah, Labor Day, that tonic for body and soul. Some of you probably have skipped town already. Most of the rest of you are plotting picnics in the park, lazy days at the beach, cookouts, confabs and great doings.

But before you roll out your barrel of fun, give a moment's thought to the folks who couldn't make it.

Why not send "wish-you-were-here" postcards to the people who are working this weekend? You'll drop a bundle in postage, but you just may lift some sagging spirits.

Call it the lost weekend. It's the lot of more than $100,000 Washingtnians and suburbanites, flesh and blood: toll-takers, power-plant workers, airline ticket agents, mail-sorters, projectionists, bartenders, security guards, weather forecasters and crisis managers in the Pentagon: namely people without whom the weekend most of us know and love would suddenly disappear.

Wildly out of step with humanity, they and their loved ones must brave the icy indifference of government statisticians, football impresarios, garagesale entrepreneurs and most everyone else on the road to the good life.

"Labor Day is a sad time for us," says Fairfax housewife Wadonna Duncan, the mother of three small children and the wife of a White House guard whose work week runs Friday to Tuesday. "So is Memorial Day and the Fourth of July. With the radio stations and the TV news always talking about weekends, I feel like I'm living backwards from everybody else."

"It's hard on our little boy," reports Wadonna's husband, Steve, of their three-year-old's reaction to his work days. "He's always asking me, 'Daddy, why can't you be home on Saturdays?' because he wants to go on picnics with his friends and their fathers. How could he possibly understand something like that? All I do is try to make him feel better in the middle of the week."

The Duncans, it might console them to know, are not alone.

There is, for instance, Gary Wolfe, an air traffic controller, who wonders if he'll ever take his 7-month-old daughter to meet her 91-year-old great-grandfather at the Father's Day family reunion in Christiansburg, Virginia. "I've made it to one in the last five years," Wolfe says. "How long can the old man last?"

There's Andrew McCoy, 50, the night-weekend administrator of D.c. General Hospital, a tennis buff who lives in Oxon Hill. In hopes of a Saturday or Sunday pickup game on his way to work, McCoy always keeps rackets and balls in his car, and "If I see somebody on the courts, I'll stop," he says.

And there's Ellen Wedge, a bartender at The Man in the Green Hat on Capitol Hill, who mixes drinks Wednesday to Sunday, and often mixes in bars on her Mondays and Tuesdays off. "I really don't drink that much," she says. "I just like to stop by and see my friends. A lot of them are in the business."

Nobody seems to pay them much attention or, for that matter, know they exist. Not even the Bureau of Labor Statistics, that font of facts about everything, bothers with them. Considering their importance in our leisure-support system, stunningly little is known about the weekend workers and their lives.

"Ya know." muses Studs Terkel, the high priest of the working class, "I never even thought about them." Et tu, Studs? Say it ain't so!

Back in the USSR, the Russian calendar fairly brims with The Day of the Irrigtors, The Day of the Geologists, The Day of the Metallurgists, The Day of the Merchants and The Day of the Border Guards (by way of a modest sampling), but no honor goes to the weekend toiler.

"This is somethig novel to me," Soviet Embassy staffer Boris Davidoff says when asked if the Politburo has considered such a holiday. And as a measure of how invisible American weekend workers truly are, Davidoff is all agog at the notion that some Americans actually do work weekends: "No! Really?" The United States, of course, has Labor Day Weekend, but alas, no Weekend Labor Day.

"The time and structure of people's jobs and work lives plainly are changing," says industrial psychologist Stanley Seashore of the University of Michigan. "It's apparent that more people than, say, five years ago are working two jobs or shifts other than regular day shifts, that more people are working weekends or unscheduled hours -- some of them simply meeting the demands of a changing economy. For instance, more people are eating out, so they need more cooks and waitresses working to feed them, and there are more people working in entertainment of various kinds."

A survey conducted by The Washington Post in 1977 suggested that more than twice as many people who worked weekends than those who did not were divorced or separated, and that weekend workers generally earned less money than their weekday counterparts.

All this boils down to the conclusion that weekend workers, like the Kurt Vonnegut character, Billy Pilgrim, are unstuck in time -- and many of them, apparently, are having less fun than the rest of us. Which shouldn't be the case, Dr. John Neulinger argues.

"I hate that expression, 'leisure time,'" says Neulinger, a City College of New York psychologist who is one of a burgeoning breed of leisure theorists. "Leisure has nothing to do with time because, obviously, you can have free time and not experience leisure."

What matters more, Neulinger says, is one's "capacity to leisure" ("It's a verb," he suggest), which depends on such imponderables as attitude, environment and upbringing.

Here are some sketches of weekend workers and how they cope: AIRLINES TICKET AGENT

Five mornings a week, Barbara Ford pedals her bicyle from Alexandria to National Airport. Stationed behind the ticket counter for eight hours, she pushes buttons at a computer screen and dispenses plane tickets. On some days, Ford stands in the main terminal, poised to unravel the tangled emotions of some late -- arriving passenger.

A Vermont native who has lived in Washington a year, Ford, 24, likes her job, but by Tuesday she's ready for a break. "From my perspective, having weekdays off isn't all that bad," says Ford, whose odd days off have been Wednesday and Thursday since early June. "It's true that most of my friends are on regular schedules with weekends off, but sometimes I can swap around a bit, so it all works out."

Yet Ford usually would rather work than swap. Because, she says, hitting the beaches of Maryland and Delaware, waterskiing on the Chesapeake, white -- rafting in Virginia's Shenandoah National Park and visiting the museums of Washington are all much simplier during the week.

"Everything's just nicer without the crowds," she says. "It's easier to get reservations for things."

Other ways Ford says she has spent her weekdays off: taking advantage of cut -- rate matinees, playing the wide -- eyed tourist in the Senate and House galleries, shopping at Baltimore's Lexington Market and attending the Kennedy Center's regular town meeting on Thursday morning.

Of course, Ford, like most people, sometime tires of the Washington scene.

When that happens, she just hops a jet to Miami or Aspen -- for free. AUTOPSY TECHNICIANS

It's not exactly the sort of work one likes to bring home.

So Eugene Compton and Wilbur Rowles, who together have worked the D.C. Morgue's night -- weekend shift the last 10 years, fielding crank calls for "Myra Mains" during the slow times, put their jobs far out of their thoughts on their Mondays and Tuesdays off.

Compton, who rents a place in Suitland during his Wednesday-through-sunday work week, usually escapes to Maryland's Eastern Shore, where he owns a house, on Mondays and Tuesdays.

"I like fishing and I do a lot of gardening. I plant everything you can think of -- cabbage, stringbeans, tomatoes," says Compton, whose four children have grown and gone. "Sometimes I don't care much for the schedule. Most of my friends seemed to have vanished. They get so they don't call anymore. But I don't feel isolated. I don't even think about it."

"We're not the sociable kind," says Shirley Compton, who from time to time has worked as a barkeep and waitress. "We don't party a lot. Mr. Compton just works in the garden and I do some canning. I love to can. Sometimes our children viist and they take away canned vegetables."

As for Rowles, he lives with his wife and 18-year-old daughter in Arlington, and says he spends much of his free time watching TV. "We like sports -- football, baseball and basketball," Rowles says.

"Sometimes we'll go to the Washington and Lee footbal games, but we never go to Baltimore to see the Orioles."

Other times, Rowles says he'll "see a good movie, like a western, The Godfather or Jaws . Or maybe the wife and I will have a picnic in Turkey Run Park. Or go shopping. I pretty much stay out in Virginia. I don't like to travel too much anyhow." POSTAL WORKER

In the beginning, Vincent Gray says, there was "loneliness and solitude." But now, reports the 36-year-old parcel distributor, "I've outgrown all that."

Gary, who has worked a Thursday-through-Monday schedule at the city's Capitol Hill post office the last nine years, says it took him a long time to sort out his life.

"I don't have much contact with people of my own age group because they're off on different days," he says. "You might say I've had to adjust. It was either that or go crazy."

A resident of Prince George's County, Gray says work is dull and his Tuesday and Wednesdays away from work usually are quiet. Gray spends some of them with his young son, who lives elsewhere with his mother, occasionally taking the boy to a park or movie. But mostly he watches soap operas, reads or meditates at home. p

"I do something called 'God Realization," Gray says. "It's a type of yoga, or at least it serves the same end.I don't follow any strict rules about it, but usually I'll mediate a couple of hours a day. You have to think of nothing. That's the hardest part." TOLL COLLECTOR

When thousands of weekends travelers head for Ocean City, Martara Hannah is there to wave goodbye. Most Saturdays and Sundays, she's trapped in a toll booth on the Bay Bridge near Annapolis, breathing exhaust fumes and making change.

"It makes it hard to smile," says Hannah, 22, of the job she's held the last three years, "Standing in a toll booth all day, with busted veins in your legs, you get a little envious of people who go places on weekends."

Hannah, who lives in Glen Burnie, nevertheless sees some advantages to her rotating schedule, which puts her on the toll plaza six weekends out of seven:

"The stores and the banks are a lot less crowded in the middle of the week. It's easier to get a court for racketball or tennis. And since most of my friends are on day work, when I get off at three, I still get a chance to see them." INSTA-CREDIT GRANTER

Mabel Henderson, a 42-year-old widow and the mother of seven, spends her Saturdays and Sundays in a telephone boiler room atop the Kennedy Center. There, Wednesday through Sunday, she obliges callers, some of them cantankerous, who wish to put their show tickets on any number of major credit cards.

Over the incessant ringing of phones, she delivers herself of a peroration.

"If I want to take off for a weekend trip to get away from this job, it's just not possible. I know, I've tried. I have a friend, but he's a bricklayer who's off Saturday and Sunday. He doesn't like to do much. He doesn't like to do anything. My kids call him The Coffee Man. Every time he comes over, the first thing he says is, 'You have a cup of coffee?' Sometimes I go to dinner with my mother and sister, but I ask you, how often can you go out with mama? You need to have some leisure time, but it's not too fun by yourself. It's a nowhere job in a nowhere life. Strictly dull, dull, dull."

She signs some more, and adds: "Mostly I grab me a Harlequin Romance and a Champale, and stay home." PEPCO WORKER

"How much fun you have depends on the people you're with," says Lou Fiel of Cobb Island, Maryland. "In my case, it's usually with somebody who's umemployed."

Fiel, 47, has been in one job or another at the Potomac Electric Power Co.'s Alexandria plant for 23 years. As a member of the plant's "Gang 901," a designation for everyone with his particular schedule, he toils at the boilers six weekens out of nine, and also contends with the wild hours of a shift worker.

Fiel blames the recent breakup of his 25-year marriage largely on a "crazy schedule" that has him working every hour of the day and night. "I've been home one Christmas in the last 12 years. I hardly know my children."

Fiel says he has sacified and worked a lot of overtime to keep Washington in watts and volts, but hasn't stopped him from having a good time. On days off he plays golf, softball and tennis -- sometimes, he says, with people who do have jobs -- he also likes to revv up his Suzuki 850 motorcycle for a weekday jaunt and fish from a friend's sailboat.

"That's what I'm doing this afternoon, going fishing," Fiel announced one recent Friday as he smoothed out his long, black mustache. "Tomorrow morning at seven, I'll be back at work." METEOROLOGIST

"Sailboats," Bob Werner says cooly, "are not for fishing."

It's Sunday afternoon and Werner, as usual, is holding forth amid radar scopes, satellite pictures and computer terminals on the third floor of the World Weather Building in Camp Springs, Maryland.

From Friday to Tuesday, as he has been the last 10 years, Werner is the National Weather Service's lead forecaster for a three-state region, issuing watches and warnings to the populace; Wednesday and Thursday, if the weather's right, he'll likely skipper his sailboat into Chesapeake Bay.

"On weekends," says the 50-year-old Werner, whose face wears a perpetually wry smile, "the bay is so full of boats you can practically walk on the water. It's a lot better during the week."

Now that their five children are grown or in school, the Werners say they are discovering some joys in weekday leisure. Besides sailing, these include drives along the waterfront, solitary walks and bike rides, quiet lunches together, and matinees followed by unhurried suppers out.

"I always tell him that I won't have to go through a big traumatic change when he retires," Joanne Werner says. "I like having him around."