LOS ANGELES -- Sailors do it. Retirees do it. Corporate presidents do it. And you do, too, for something like 43 hours a week.

Americans spend more than one-third of their waking hours in the pursuit of leisure. Many feel they don't get enough leisure time, but a lot of folks have trouble deciding just what to do with all that free time.

And that's where Bruce Morehouse comes in.

Morehouse has the kind of job college students dream about: He is a leisure consultant. He has a Ph.D. in leisure behavior from the University of Illinois and is president of Leisure Co., a new service based in Santa Monica for people who need help figuring out how to play.

The affable Morehouse expects guffaws from those who think leisure should be a cakewalk. "I can just hear it: 'You won't believe what they're doing in California now, they're paying people to tell them how to have fun,' " he deadpans.

But leisure is serious business, as evidenced by the U.S. Navy's request that Morehouse draw up a game plan of leisure activities for personnel at the Long Beach Naval Base. The Desert Hospital in Palm Springs also has enlisted his services for drug-dependent teen-agers and obese patients recuperating from "bubble implant" surgery.

And corporations hire Morehouse to set up recreation programs for harried executives and pre-retirement planning seminars for senior employes.

For the past month, Leisure Co. has been making a pitch to the general public with local radio ads featuring the immortal "So whaddaya wanna do tonight?" line from the Oscar-winning film "Marty."

Since the ads began running, nearly 200 people have mailed in $39.95 for a computerized leisure profile and six recommended activities.

Why does free time pose such a dilemma? Morehouse believes the work ethic, which he says has been "carried to extremes in our society," puts pressure on people to excel at everything, even play.

He also believes the cornucopia of available leisure activities (the Leisure Co.'s inventory lists 150) has become "an overabundance of riches."

"People tend to stack up their leisure time -- 'I'm going to play tennis from 2 to 3, then I'll shower and meet a friend at 4,' " he says. "No one seems to be able to just relax."

The physical-fitness boom has further complicated the leisure picture because people now feel compelled to spend much of their free time getting in shape.

Says Harriet Svirsky, Morehouse's associate: "You say to yourself, ' ... I have to be physically fit and look good.' But what if you don't like aerobics?"

If you don't like aerobics, you might need an activity with more of a risk-taking component or less of a competent component. Morehouse has turned leisure into a science of sorts. Like a chemist, he has broken down each of 150 activities (ranging from airplane flying to yoga) into five components -- mental, social, competent, solitary and risk-taking -- which are the building blocks of each client's leisure profile.

"This isn't a computer dating service or a program that says, 'Hey, we think you'll like tai chi,' " he says. "This is based on solid research."

Morehouse began by distributing a 40-item questionnaire to enthusiasts in each of the 150 activities. Their descriptions of what they enjoyed about their sport or hobby were compiled for a profile of each activity. New clients fill out the same questionnaire and Morehouse selects six activities that closely match their profiles.

Mark Jason, Morehouse's partner, reports that many people come away with a whole new definition of leisure.

"We had a racquetball player and a golfer who were both playing their games like crazy -- real Type A behavior -- and they just weren't satisfied," he recalls. "So we recommended a couple of fairly passive hobbies for each guy to calm them down, and their mental health really improved."

The founders of the Leisure Co. agree that their business could only have sprung up in Southern California ("This seems to be the center of new trends and fads," says Morehouse) but they say the idea will catch on elsewhere.

Meanwhile, to keep their inventory fresh, the consultants are dutifully scoping out local beaches and parks to spot new fun things to do.

Morehouse says he may have found the Leisure Co.'s 151st activity. "Disc golf -- a lawn game played with Frisbees and hoops -- is catching on now," he reports. "I've also seen some disc football, but I think it's too new yet."