In late 2014, Susan Schlacter and her husband, Jed, were discussing what to get each other for the holidays. “We really didn’t need a thing,” recalled Susan, 62, an IT professional. Except, maybe, a more active lifestyle. “Over the winter we’re not able to get out and go biking and walking as aggressively as we like to,” she said, recalling their conversation. “So what can we do?”

The solution they hit upon was one that’s become more common with busy people who want to get in better shape: They decided to hire a personal trainer to come to their home in Roslyn, starting in January 2015.

Robin Pemberton, the trainer they hired, was ready. “I usually pick up a few clients at the beginning of the year,” says Pemberton, who lives in Roslyn Heights and has been a personal trainer for 19 years. “They say, ‘It’s time. . . . I need to take more of an interest in my overall health.’ ”

For busy trainers like Pemberton, an independent contractor who sees clients in their homes as well as at a local gym, D-Fine Fitness in Albertson, “time” is the operative word. “You have to work according to people’s schedules,” says Pemberton, 55. “But that’s what personal training is. It’s geared to servicing your clients.”

Once a luxury for the privileged few, personal training is now mainstream: According to the Bureau of Labor Statistics, there were 279,100 fitness trainers and instructors in the United States in 2014 — a number expected to increase by 23,400 over the next decade. Qualified trainers are those certified by one of a half-dozen reputable fitness organizations, ensuring that they’re not — ahem — dumbbells, but rather, fitness professionals who can prescribe safe, effective exercise programs for all ages and abilities.

Pemberton, who is certified by the American Council on Exercise, brings expertise, experience and creativity to the job. Not to mention equipment. While some of her older, mostly North Shore clientele have extensive home gyms, many own just a few pieces of exercise equipment. She supplements that by bringing stability balls and kettlebells.

Trainers like Pemberton who travel to clients’ homes — and there are hundreds on Long Island — do little advertising. “It’s mostly word of mouth,” she says.

advertisement | advertise on newsday

Still, business can come and go. A few years back, veteran trainer Bob Phillips, who lives in Melville, lost four longtime clients through a combination of factors — relocations, scheduling problems, medical issues. “That’s a significant portion of my business,” says Phillips, now 54. Though he was able to replace them, it shows the precarious nature of the business. “I think the rewards of what we do can be really great,” said Phillips. But “you don’t have the stability or job security you have in other occupations.”

Also, not everyone is realistic about what a trainer can achieve. “Managing expectations by clients is one of the hardest things,” says Pete McCall, a master trainer and spokesman for the San Diego-based American Council on Exercise. “If you’re not doing the other things to support your efforts in the gym . . . proper nutrition, sleep and so forth . . . then you’re not going to get results.”

Another problem for trainers is time off. They need to be available when their clients are — and that precludes long absences. “If you’re the kind of person that wants to travel a lot, I’d say this might not be the best occupation,” says Phillips.

Reciprocal agreements to cover for each other during absences — as physicians do — are not unheard of in personal training. But, acknowledges McCall, “some trainers are a little fearful of it,” out of concern the client will prefer the substitute.

Often, the biggest challenge for experienced trainers isn’t finding new clients; it’s finding a time for them. “You only have one 10 o’clock on Monday morning,” Pemberton says. “Some people don’t understand why they can’t get that time, when I have a client of 10 years who has that slot already.”

Like most good trainers, Pemberton has proved herself a master of time management. Because a trainer’s own training is important (who would hire someone out of shape to get them into shape?) she is usually up by 4 a.m. and out the door to the gym for her own workout by 5 a.m. She begins seeing clients around 6:30 a.m., works until 12:30 and on some days comes back to train a few more clients in the late afternoon. That schedule, she said, “was great when my children were young, and still gives me a lot of flexibility.”

Flexibility was not something Susan Schlacter and her husband, an attorney, had when they first approached Pemberton about training them. They both work in the city, catch early trains and get home late. So what to do?

Pemberton offered this solution: She would train them back to back, 30 minutes each, at one of her few available time slots: 6 a.m. on Saturday morning. They took it, and two years on, Susan says she and Jed are stronger and fitter. “We both agree it was definitely a great gift,” she says. “In fact, we want to increase our sessions in the coming year.”