• A 41-year-old Pilates instructor said she's prioritizing longevity workouts as she gets older.
• She said shorter, lighter workouts help her stay energized and strong with a busy schedule.
• Her Pilates-based workouts involve strength-building exercises, mobility, and mindfulness.

When it comes to staying fit beyond 40, you have to be smart about it.

For Lia Bartha, a mom-of-two who founded the fitness app B The Method, that means low-impact exercise.

Bartha told Business Insider she spent her 20s and early 30s pushing her body to the limit doing high-intensity cardio and teaching Pilates.

Bartha knew she needed a change when she hit her mid-30s, after she had kids. She was looking ahead at how she wanted to feel in the long-term.

"I trained and taught that way for so long, I started to feel myself kind of plateauing and getting bored because it was so rigid. I felt like it wasn't necessarily intuitive in how my body was aging," Bartha said.

So, in 2018, she developed her own method, an online fitness brand that incorporates Pilates along with other wellness techniques such as breath-work and gentle movements to subtly tone muscle.

The shift from classic Pilates, and big equipment like reformers, was a better fit for her body as she got older — and drew in thousands of subscribers globally. Bartha has worked with celebrity clients like Aubrey Plaza, Cynthia Erivo, Ego Nwodim, and model Martha Hunt.

"It's thinking in this bigger way of, how is supporting my body for the end of the day?" Bartha, now 41, said. "I'm a mom of two girls, so I have this job of working out and I'm teaching and then I'm doing the business side and then I have to take on this extra shift of taking care of them and feeding them. I think the exercise really has to help you mentally."

10 minutes is plenty of time to work out

As a younger athlete and dancer, Bartha said she spent hours on cardio or intense exercise to stay in shape, but adjusting her workouts to a packed schedule has taught her to do more with less.

"I was kind of just doing what everybody else was doing. I was like, OK, I'm going to get on the treadmill and just walk or run forever," she said.

Now she often works out for less than an hour, and designs workouts that are just as challenging and effective in 20 minutes.

The benefit of shorter sessions is that it's easier to commit to them every day.

"It doesn't have to be 45 minutes or an hour all the time. If you're giving yourself 10 minutes a day very consistently, you'll see huge benefits," Bartha said.

Low-impact exercise is a gentler way to train

A big shift for Bartha was learning that exhaustion and sweatiness isn't the best indicator of a good workout.

"You don't have to go through an aggressive workout that leaves you very sore and fatigued to have all of the benefits of exercise," she said.

Low-impact workouts like Pilates tend to emphasize slow, controlled movements instead of fast, explosive techniques. As a result, they're easier on the joints, and don't take as much recovery time afterward.

Low-impact techniques like isometric movements have many of the same benefits as higher-intensity training in helping to build strength and muscle. They can also improve factors linked to longevity, such as stability and balance.

"We want to think of the body in the long term, and I think that's where low-impact is just so important," Bartha said.

Consistency is key

Bartha said she fell into the trap of pushing too hard instead of developing an enjoyable, sustainable routine.

"One of the most common mistakes that people have in terms of fitness is just getting through it to get through it," she said.

She said listening to her body and taking it easier led to better results, with less work, because the workouts left her feeling energized instead of depleted. As a result, working out felt less like a chore and more like something she could do every day.

"It's finding your body where you're at," Bartha said.

• I became a Pilates instructor 11 years ago, and I've since built a successful side hustle.
• I've made over $20,000 annually from teaching classes, which helped me switch careers.
• I love connecting with clients and strengthening my muscles during each class.

As a competitive runner for most of my adult life, I struggled to balance my love for intense cardio with proper stretching and strength training — until I discovered Pilates.

When I took my first Pilates mat class at my hometown YMCA in 2005, I instantly fell in love with the low-impact, full-body workout.

The exercise was fun and challenging, and I was excited for each class. This was also the first time I looked forward to going to a gym for anything other than cardio.

So, when my studio offered a teacher-training program, I signed up. At first, I was solely interested in deepening my own Pilates practice, but after leading group classes and private sessions during an apprenticeship, I realized I loved teaching and could make money doing it.

I've now been teaching Pilates for about 11 years and have no plans to stop.

Working as a Pilates instructor turned out to be a great side hustle

When I committed to becoming an instructor, I was burned out from my job as a freelance publicist.

However, I realized teaching classes meant I could earn a decent amount of money. My Pilates income — which, some years, reached over $20,000 annually — made it financially possible for me to transition to a new career as a freelance writer.

As a teacher, my studio paid me a flat rate for classes and private lessons. I also received bonuses for high attendance — an incentive to build my client roster and make lessons more fun using creative playlists and props.

Plus, I often subbed for other teachers to supplement my income.

I was able to build a fitness community and strengthen my body

Over the years, I've built a core group of clients and have developed close relationships with other instructors. I still socialize with them regularly, even outside sessions.

When the gym I worked at closed in 2017, several students even followed me to a new studio to take classes, and others came to my home to keep up their regular sessions.

In 2020, when the COVID-19 pandemic meant in-person teaching was not an option, I launched virtual Pilates classes that helped me keep up with my own practice and connect with others.

Outside of the friends I've made, I also love the way Pilates makes me feel, and the workout has taught me to slow down and connect to my body. From the first set of "the hundred" — a traditional Pilates warm-up — to the final push-up or stretch, I learned to move intentionally and precisely.

The exercise has helped my body feel stronger, fitter, and faster, and, as a runner, I still like to incorporate some moves into my pre- and post-run routine.

I don't teach as much these days, but I still make some extra cash

Today, I don't teach at a studio or make as much money as I used to, but Pilates is still a great side hustle for me.

I'm able to earn extra income and connect with my favorite students through virtual classes and one-off private workshops and events.

If you ask me, you can't beat a side hustle that allows you to meet amazing people, make money, and do something great for your mental and physical health.