The best battle plans are made of small steps, according to celebrity fitness trainer Erin Oprea.

When it comes to strength and training, the Nashville-based instructor and Marine Corps combat veteran knows what she’s talking about. Oprea currently trains country music stars including Kelsea Ballerini, Kacey Musgraves, Maren Morris, Lauren Alaina and Florida Georgia Line, but she was once chosen to lead the first all-female platoon attached to the infantry in a war zone. She cites her military background for making her who she is today.

Starting the New Year strong, Oprea spoke with Fox News about all things health and wellness — including her tips on how to stick to fitness resolutions, how she keeps her A-list clients feeling motivated, and what the Marines taught her.

When it comes to strength and training, the Nashville-based instructor and Marine Corps combat veteran Erin Oprea, pictured, knows what she’s talking about. (Fox Digital)

FOX NEWS: What are your tips for pursuing – and sticking – to fitness goals in the New Year?

ERIN OPREA: I like to set small, attainable goals. Instead of saying, “I need to lose 50 pounds,” make small goals, like weekly ones, so you can check it off. Any time you have that sense of accomplishment, it makes you feel better. And it makes you want to keep going.

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“I like to set small, attainable goals. Instead of saying, “I need to lose 50 pounds,” make small goals, like weekly ones,'” says the trainer to the stars. (Zac Harrison)

FOX: You served in the Marine Corps from 1997 to 2006, including a two-year tour of Iraq. How has your military experience inspired your passion for fitness today?

OPREA: I feel like my military [experience] has completely made me who I am. It gives me my discipline to keep me going every day. My life is very structured. I had a love for fitness before I went in, but I learned so much about my body, and how much your body can do, while I was in the Marine Corps. So I feel like everything that I learned while I was in, I took into my career now. I feel like I’ve had the best of both worlds!

FOX: Will veterans recognize any military training moves in your workouts?

OPREA: Absolutely. In the Marine Corps, we did a lot of bodyweight training. So, of course, good ol’ Marine Corps push-ups, flutter kicks, squats, all the good stuff. Those are the foundation of my workouts.

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Celebrity fitness trainer Erin Oprea works with some of the fittest names in country music, like Kacey Musgraves, Maren Moris and Kelsea Ballerini (pictured left to right.) (AP)

FOX: As a personal trainer to some of the fittest names in country music (like Kelsea Ballerini, Kacey Musgraves, Maren Morris, Florida Georgia Line, Lauren Alaina and Jana Kramer), do you have any fitness tricks for getting your clients feeling energized and ready for big events like concerts or award shows?

OPREA: Some of the best tricks are to getting everyone feeling amazing is getting their confidence up. If I can make them feel good, not just physically but mentally, I feel like it all plays out. You put them on a red carpet, and they’re like “Yeah! Look at me!” Tricks for getting them feeling their best [include] making sure they’re eating clean … and we have lots of fun workout games we play.

FOX: When your clients are on the go — on the road, on tour, doing appearances — what moves do you recommend if they only have a few minutes to workout?

OPREA: Tabatas are my absolute favorite. A tabata is a four-minute workout – 20-second bursts of exercise, followed by 10 seconds of rest, for eight rounds. And it will burn so many calories, and it will have you feeling breathless, winded, but feeling amazing and energized, which is the best part.

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FOX: Congratulations on your new app, Pretty Muscles. What are you most proud of about it?

OPREA: I’ve worked so hard on this project. I’m proud of the fact that every day is a different day for the whole year. No workout is repeated. So I’m proud of it being different than what’s out there, how much work I put in and I hope my passion shows through in all the workouts out there.

Fitness and workouts don’t “have to be structured,” Oprea says. (Ryan Sims)

FOX: On a typical day, what’s in your gym bag?

OPREA: I always have my Poise [products], water, my Dymatize protein powder and my jump rope, of course! My jump rope is like my best friend.

FOX: Beyond the gym, what are your wellness tips for a balanced lifestyle?

OPREA: Of course, eating clean is definitely a huge part of it. But movement, all-day movement, is super important. Yes, your workout is important, because you have to build those muscles. The more muscles you have, the more calorie you burn at rest.

I encourage everybody to just get out and walk. [It’s] great to bring your family into it, because that’s family time. Go play sports with your kids. It doesn’t have to be structured. Go and move, make it a lifestyle… because then you feel good and you want to keep doing it.

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FOX: Is there anything else you’d like to share with our audience?

OPREA: I want to tell everyone that they’re worth it. I don’t care what they’re thinking, what their size is, what they’re going through emotionally … they are worth feeling amazing. Everybody is worth it.

Watch the video above for Erin’s must-have moves for toning the arms and back for tank top season.