Going from lipstick and skinny jeans to messy buns and yoga pants sometimes indicates that parenting produces new priorities. But when one mom had it pointed out to her, it was her own response that made her want to change the conversation.

Amy Weatherly, 34, a mother of three and blogger from Texas, shared a Facebook post that's resonating with thousands of moms about a recent encounter with an old friend who said to her, “I can’t believe I’m seeing you out in public with no makeup and tennis shoes," followed by the question, "Who even are you anymore?”

"Yeah, something about that third baby really forced me to let myself go,” Weatherly replied.

But Weatherly told "Good Morning America" that her own response left her disappointed.

"I have heard so many of my friends use the phrase," she said. "Because I've heard it a lot, I know it's something [women] think about. My friend's not the one who said it, I was the one who said it [about myself]. She wasn't being mean or catty, she was making a very true observation.”

"I think maybe it's a defense mechanism," she added. "We feel if we call it out first then it won't give anybody else the chance to."

Weatherly admits that she has transformed from being the girl who cried over a breakout to feeling more confident and sure of who she is now. She shared the post in hopes other women would feel empowered and no longer use the phrase, "I've let myself go," but instead focus on what truly fulfills them. For Weatherly, that meant less worrying about throwing big birthday parties and looking pretty, and more worrying about being a good mom to her kids.

"I knew I didn’t look the same as I did before, but had I actually let myself go?" she wrote in the post. "Ten extra lbs and a messy bun would point to yes, but my heart screamed “HECK TO THE NO YOU HAVE NOT, GIRLFRIEND."

She went on, "You haven’t let yourself go. Stop saying that. It’s rude. It’s derogatory, and it’s downright absurd. You haven’t let yourself go, you have simply let go of the need to look perfect all of the time. You have simply let go of stuff that isn’t important and traded it in for stuff that will leave a lasting legacy. You have simply let go of stuff that will last a little while, for stuff that will last for generations and generations and generations.”

"Put on makeup when you can, get your hair did when you find the time, pamper yourself, take care of yourself, splurge on a new outfit and don’t you dare feel bad about it for one second -- just know that none of those outside things define you," Weatherly wrote. "Not anymore. They aren’t you. They are things, and there is a huge difference between the two."

Weatherly's post, which was accompanied by a no-makeup photograph of herself posing alongside her 2-year-old daughter, garnered over 1,000 likes and hundreds of comments from mamas who said they can relate.

"The fact that it has reached so many women, it blows me away," Weatherly told "GMA." "If it makes women feel encouraged and feel beautiful, I am happy that I can play that small part.”