Atlanta (CNN)In her prime, Julie Mignerey was on her high school swim team.
The statuesque woman grew up in a health-conscious household. Her father played professional football, and her mother, she says, was "fit and healthy."
Fast-forward to 2018: Mignerey is 48 and married, with four teenagers. Staying fit is harder now.
"I felt healthy my entire life until the last few years. As age has crept up on me, I noticed little things -- going up the stairs with a full load of laundry, I'm a little out of breath," she said. "Go hiking with my family, and I'm the last one in line."
It wasn't a good feeling, the suburban Atlanta mom says.
Mignerey tried to walk her dogs more often, get on the treadmill at home and take online yoga classes -- but it wasn't enough.
"I needed an inspiration," she said. "I needed someone there who was going to push me and be more accountable for what I was doing."
But Mignerey, who works as a real estate manager for a hotel site-selection company, was intimidated by "no pain, no gain" gyms. And she didn't want to spend money on a personal trainer.
"There's no way I'm going into a gym where these people are very hardcore," she said. "I'm going to be burnt out after the first time and be discouraged."
Getting stronger without getting injured
Then, Mignerey discovered a small gym near her home that fit the bill.
It specializes in functional fitness with the goal of making everyday tasks easier: being able to walk up a flight of stairs without getting winded or lifting a gallon of water without wrenching your shoulder.
"Functional fitness" is the same term used for workouts at many CrossFit gyms, but middle-age clients with creaky knees often find those places too hardcore.
Mignerey's new gym asked about her health, medical history and personal goals before she started her first class.
"They spent a lot of time with me," she said. "They had me do certain exercises and asked, 'How does that feel? Where are you feeling that?'
"And that continues today when I'm in their classes," she added. "They will come around and say, 'Now, here's where you should be feeling it. You need to adjust.' "
What questions your gym should be asking you
That questioning is something all gyms should be doing, says Walt Thompson, president of the American College of Sports Medicine Research and professor of kinesiology and health at Georgia State University.
But, Thompson says, gyms with lots of clients often don't take the time to go through consultations.
He says there's a strong possibility that new clients can get injured, since many Americans don't have even a basic level of fitness before walking into a gym.
The class Mignerey takes is low-impact: no jumping or heavy lifting. You move from station to station and use such equipment as ropes or small kettlebells that work different muscle groups.
"We have to be able to do a squat that's safe and effective for when you're sitting in a chair, getting into a car, getting off the couch," said Kolleen Losch, a personal trainer and owner of Core Physique in Alpharetta, Georgia. "Those are all functional movements."
Mignerey's class has only 12 people, which allows for more one-on-one attention from instructors. Thompson says small classes are something you should seek out if you haven't exercised in a while.
In Mignerey's class, most of the participants are over 40, a less-intimidating age group for this woman making a comeback.
Safely squatting, lunging, pushing and pulling
As a novice, Mignerey learned the basics like how to properly lift a kettlebell. The instructor taught her how to do a modified plank and push-up.
Mignerey wasn't shy about asking, "Is this where I should be feeling this?"
"Exercise should not be about getting injured. It should not be about bigger, stronger, tougher," Losch said. "It should be about getting you stronger so you can take those baby steps to get your body in the shape that you need to get it in."
Losch emphasizes that human bodies don't lose muscle capacity in one day, so clients shouldn't expect to see immediate results, either.
"It's going to take a while," she said.
Mignerey has gone to class three days a week for the past several months.
After about two months, she says, she noticed her aches and pains going away and her posture improving.
"I feel like my muscles are stronger, and they support me better."
Her trainers also talked with her about adding fresh vegetables and fruits to her meals. Now, she said, "the more I work out, the better I eat, the better sleep I get."
"I feel more alert from the time I wake up until I'm ready to go to bed."
And she's losing weight. "When I sit down, I don't feel as if I'm as soft everywhere," Mignerey said with a laugh.
Gyms are not regulated, so ask questions
Mignerey is having a good experience with her gym. But Thompson says consumers should be careful when choosing a fitness program.
The professor spent years as an expert witness hearing about injuries resulting from gyms.
Thompson says there are no firm numbers related to serious injuries in gyms, due to many cases settling out of court and gyms not being honest about injuries.
"I would interview the physical therapist or fitness instructor just like I would interview a plumber, an electrician or a doctor," Thompson said. "I would ask questions like, 'What is your education?' ... 'What is your certification?' 'What kind of experience do you have?' 'Have you worked with somebody like me?' "
If the trainer says they've never worked with anyone your age, Thompson says, walk out the door.
"Not a single state in this country regulates gyms, which is astonishing," he said. Neither do any states require licensing for personal trainers or fitness instructors, Thompson says.
As a result, he says, there are more than 250 ways to earn certifications in the fitness industry.
"If we had access to a laptop and a good credit card, we could be certified to be a personal trainer by six different organizations" within minutes, he said.
Thompson has teamed up with fitness organizations to create the not-for-profit US Registry of Exercise Professionals. The organization reviews certification programs in the fitness industry and makes sure they meet widely accepted minimum standards.
There are more than 148,000 registrants in his registry, and it's growing, but not all trainers are on it.
You can also check the Institute for Credentialing Excellence, which looks at all organizations with certification programs, including those in the fitness industry. If you know the name of the organization that your fitness instructor got his or her credentials from, you can see if it pops up there.
Take it slow
Even if a gym does its due diligence and asks you about your goals and your medical history, it's ultimately your responsibility to communicate what your injuries and limitations are.
"Are there any exercises you feel might hurt you? A good trainer will know how to ask the follow-up questions," Thompson said.
A reputable fitness trainer will know how to design a workout for you, give you modifications or request that you see a doctor before you take part in their course, he says.
So how do you know if you're overdoing it while exercising?
"Normal is a burning in the muscle, shakiness and fatigue. What's not normal during an exercise is joint pain," said Sabrina Jo, director of science and research content for the American Council on Exercise.
"Anything that tends to signal pain directly in the joint or around the joint, that's when you want to back off."
If you haven't exercised formally in several years, start off slowly, Thompson said. Don't jump into a high-energy program where you may pull a muscle -- or worse -- in the first 20 minutes.