Carrie Underwood No Longer Works Out to 'Be a Certain Size': I'm 'Playing the Long Game'

Carrie Underwood's fitness journey is forever evolving, and the country music superstar believes she's at a good place now that her "goals have shifted."

The 39-year-old singer recently spoke to PEOPLE about the new priorities she has when it comes to maintaining a healthy lifestyle and balancing her life on the road.

"I feel like earlier in my career I was working out more to be a certain size or fit into a certain aesthetic that I thought I wanted to be," she tells PEOPLE about kicking off her career at age 22 after winning American Idol. "And now I feel like I work out more to be strong and to have energy and longevity."

Underwood, who is also a spokesperson for all-natural sports drink BODYARMOR, said now that she's a mom to sons Jacob, 3, and Isaiah, 7, she wants to take care of herself just so she's able to be around for her kids for as long as possible, and actually be able to keep up with them.

"It really is playing the long game, right?" she says. "I've worked out a whole lot and been frustrated because it wasn't the results that I wanted. I feel like now at this point in my life, you really do learn that it is a lifestyle, it's balance. It is overall taking care of yourself."

Because the Grammy winner finds that her hands are usually tied at home with her children, whom she shares with husband Mike Fisher, she admits it's easier to keep up with a regular fitness routine whenever she's on the road. Underwood is currently preparing for the second leg of her Denim & Rhinestones arena tour.

"When I'm at home, I feel like I'm mom-ing it. I'm doing the laundry, packing the lunches, I'm always cleaning," Underwood explains. "So when I'm on the road and I live on a bus or in a hotel room, I'm not having to do all that stuff so it frees up a little time. My schedule is still very regimented and there's all this stuff that I do, but my mornings are a little bit more flexible."

The "Before He Cheats" singer says that keeping up her fitness is essential to make it through her concerts. "It's surprisingly physical being on stage — there's a lot of cardio. I'm running around in heels and I honestly write songs that I don't give myself time to breathe," she quips.

Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.

Underwood explains that she — with the help of her trainer Eve Overland — likes to run on the treadmill, lift weights and do banded exercises to stay in shape. However, when she's on the road she says she keeps a "make it happen however it can happen" mindset, noting her fitness app, fit52, whenever she doesn't have access to a lot.

"You have to work around a lot," she adds. "We have an app called fit52 that I'm glad to have in my pocket on my phone. So somebody can kind of tell me what to do with minimal equipment because it depends on what hotel we're in, or what we have to work with. We just make it happen when it can happen and how it can happen."

Underwood boasts that she's been making strides since her focus became overall health and longevity. She says she's very in tune with her body and prioritizes all aspects of wellness, whether it's eating clean foods or making sure she's hydrated and refueled — she usually goes for BODYARMOR LYTE's strawberry banana and orange clementine flavors.

"Just taking care of myself — moving more, eating healthy, staying hydrated — these things are all base level stuff," she says.

"If I start feeling weird or tired it's like, what boxes am I not checking? Am I eating fried food? Am I not drinking enough water?" Underwood tells PEOPLE. "Whatever it is, I usually can pinpoint what I've been lacking and try to correct that and get myself back up to speed and be able to be my best."