The singer-songwriter proved that over the weekend when she shared a shot of herself on Instagram, post-workout and sans makeup.
"I took these pics after my gym sesh yesterday (today I’m cleaning this mess of a house, which I totally consider to be my Saturday workout)," she wrote alongside the barefaced pic that showed off her perfect complexion. "This is one of my favorite new outfits...I especially love the top because this is basically my motto these days!"
The 36-year-old wore a blush-colored tank from her fitness line, Calia by Carrie, which had the phrase "I'm doing this for me" emblazoned on the front. And, as she pointed out earlier in the post, that rosy top was the perfect shade to coordinate with her freshly flushed cheeks.
"When your face matches your shirt = you had a good workout!" she wrote, adding, "Unless your shirt is blue...then maybe you should be concerned! (sorry, total mom joke)."
And the laughs didn't stop there.
Over on Twitter, the mom of two followed up her mom joke with a son joke.
"My own kid just called me 'Carefree Underwear," she explained to her followers (who were, to put it mildly, amused). "This is basically elementary school all over again."
That playground-worthy taunt came from her oldest boy, 4-year-old Isaiah.
In January, Underwood and husband Mike Fisher welcomed their newest addition, baby Jacob.
As for Underwood's post-workout selfie, it was the second post she's shared in as many weeks. In the first, she explained that she's been hitting the gym hard since she became a mom for the second time.
"I’m going to be honest, 'bouncing back' after having Jacob has been much more difficult than after I had Isaiah and I’ve been pretty hard on myself lately," she wrote. "I go into the gym and I can’t run as fast or as far. I can’t lift as much weight or do as many reps as I could a year ago. I just want to feel like myself again...for my body to feel the way that I know it can."
But she realized there's something more important than striving to get her old body back — and that's celebrating her body as it is.
"As I was working out today, I realized that for the past 11(ish) months, my body has not belonged to me. It was a perfect home for Jacob. And even now it belongs to him every time he drinks his milk," she continued. "As I prepare for red carpets and for life on tour, right now I make a promise to myself to start appreciating what my body CAN do and stop focusing on what it can’t."