Now it's couch-potato time. After ten years of boom, craze and trend, the fitness thing may be cresting. Both doctors and Wall Street analysts are concluding what my mother could have told us: Too much of a good thing is bad.

The whole industry is in for a downturn, according to Prudential Bache analyst Thomas Gettinger. As an example, he cites Armel, Inc., the company that owns the shoe boutique, Athlete's Foot, and Sneaky Feet, which took massive write-offs in 1985 and closed 19 of its 26 stores. Nike is down to $16 a share from its high of $28. Reebok took a $15 drop during the first two weeks in May. People may be foolish, but the stock market doesn't believe they're foolish enough to step up to an infinite series of $65 sneakers, no matter how grueling that 5-minute walk down Connecticut Avenue.

Pepsico sold off its ailing subsidiary Wilson Sporting Goods a year ago, feeling that the tide had turned toward Fritos and soft drinks and away from athletic equipment.

On the micro-level, there's a massive sell-off as well. Health club memberships are going for a song in the classified section of The Post -- two columns of them. At garage sales, it's a buyer's market in mini-trampolines. They're right over there next to the fondu dish and yogurt maker. Exercise bikes would be out there, too, if they didn't double so well as bedroom valets. There's not much of an aftermarket in sweatsuits, for obvious reasons, but you see a lot of them at grocery stores on people trying to hide the Dove Bars under the Nutri-Grain cereal. What first was an elite obsession has now become the province of Mr. and Mrs. Front Porch USA, and even they may be getting out.

The first signs of second thoughts came when Jim Fixx, one of the founding fathers of the jogging boom, died of heart failure with his running shoes on. Shortly after, the fitness and food faddists were unpleasantly surprised when marathoner and father of nouvelle cuisine, French chef Jean Troisgros, went to his great reward at 57 after a tennis match in Vittel, France without a trace of butter or cream in his arteries.

New York cardiologist Henry Solomon has confirmed in his book, "The Exercise Myth," what devotees of the slow lane knew all along. "Marathoners," he wrote, "are just as likely to drop dead as the rest of us."

Recently, NBC Today show's Dr. Art Ulene warned everyone to slow down and reported on a study of the American College of Obstetricians and Gynecologists that put 40 percent of the women doing aerobics on the injured reserve list; 75 percent of their teachers had suffered one kind of bone-wrenching injury or another. Doctors on the talk show circuit hint to daytime audiences that maybe they should cool it a bit. The insurance companies have released actuarial tables showing that your chances of living longer actually improve with a few extra pounds.

Closer to home, orthopedic surgeons have found a lucrative specialty: sports medicine. Dr. Sheldon Konecke, head of the running clinic at George Washington University, will send several children to college on the hamstrings of Washington's running casualties. He says business is so good repairing plantar fascias, that teeny-tiny tendon in the foot that slaps the asphalt first, that he hardly has time for anything else.

When faced with the bad news, exercise mavens wave a recent study published in the New England Journal of Medicine which found that of the 16,936 men who entered Harvard between 1916 and 1950, those who exercised vigorously lived a year or two longer than the average male who didn't. Sounds like a lot of cost for a little benefit, in any event, but especially so when you consider that Harvard graduates, with their head start on life, would be expected to live longer than the average Caucasian American, anyway. If this study wasn't a slim enough reed for the pavement-pounders to cling to, the study went on to reveal that the suicide rate among this group was 50 percent higher than the general population.

Even Jane Fonda, now that she's ruined everybody's spine, is trying to make up for it with a down-tempo video called "Prime Time," a euphemism for the stage of life people entered early as a result of doing her first workout. A lot of the pounding and jerking movements that characterized the first version are gone; the cool-down cycle begins when you've barely had time to work up a sweat. (I blame much of the excess on Jane Fonda, the way I blame all those women living in garden apartments in Gaithersburg supporting two kids on a clerk-typist's salary on Gloria Steinem. There are certain icons of the culture out there who are like dogs with bones. They won't let go until everyone's miserable.)

The fitness industry, in cahoots with Madison Avenue, also went too far. It wasn't just healthy to exercise, it was politically correct. Exercise was touted as doing all the things cigarette smoking did for the Marlboro Man a decade ago. The dress code they imposed was more stringent than the uniform at the National Cathedral School for Girls. By the time a neophyte runner had assembled the right outfit and the right gear, out they'd come with a new generation steel-belted radial running shoe.

It all would have been less annoying if people had gone about increasing their pulse rates quietly. But no, they had to bore innocent bystanders with their discussions of dual density air-vented leather upper Reeboks and their muscle-to-fat ratio.

It wasn't long before the talk at dinner parties began to affect the dinner itself. People all over town were intimidated into serving meals lower on the food chain. Broccoli started showing up in a pool of raspberry sauce calling itself a main dish. Vegetables hired a public relations firm, pulled themselves out of the ground mere minutes, it seemed, after they'd been planted, and made good their escape from the produce bin and into the gourmet section under the guise of "infant." People talked openly of doing unspeakable things to tubers and legumes. Sure, the composition and clarity of that puree of peas is first class but this is dinner, not the Phillips Collection. Say what you will about the turnip, but it's the only root vegetable that's made it through this ordeal without making a fool of itself.

My tack during these dangerous years was not to be bullied by the thought police and I timed my dining with runners to coincide with their carbo-loading periods.

Now, as I say, it's couch-potato time.

You can sit on the beach and read in peace without some jerk yelling every five minutes, "Hey, c'mon, let's go for a run. You can really give your quadriceps a workout in this stuff." Multiposition beds aren't just for the hospitals anymore. That guy hawking them on the late movie is aiming at the brie and Volvo crowd; the Vertech Back and Bed Store featuring the adjustable bed in beautiful, downtown, upscale Bethesda is doing a land-office business. "We get a lot of young people in here, a lot of bad backs, but a lot of the young ones just like to do everything in bed: eat, watch TV, work," said the store manager, Miriam Edelson. She also said that Vertech recently has expanded to eight stores, and is planning a national franchise. This is where the exercise boom is going: to bed -- the Custom-Made Split-Top Queen with separate controls, for $1606.

Perhaps we're looking at a future where the upscale trendmongers will give up their sweat-fetish to fatten fashionably in bed, while the rest of us keep worrying about our lack of exercise. No doubt the trendies are alarmed to see how fitness has reached into every level of society, just as cigarette smoking and long hair on men, once the province of an elite, have become the property of Everyman.

There's good news in all this. Those who always liked an occasional game of tennis can now get a court. You can actually ride a bicycle along the canal without being pushed in by runners two abreast. Best of all, no more of this eating in a dollhouse. Out with lapidary smidgeons of organ meats swimming in wet stuff. The trendiest restaurants in New York these days are those serving up huge slabs of charred red meat and potatoes, and hold the brussel sprouts.

It's quiet out there. Perhaps people have put aside Running Magazine for Robert Benchley, who passed along this advice: "When I get the urge to exercise, I lay down until it passes."