Mike Byerly Photography

One mom in California is being forced to defend herself for being physically fit.

Having a toned body is not normally a controversial topic, but when Maria Kang, a fitness enthusiast, posted a photo of herself in a sports bra and workout shorts alongside her three young sons with the caption "What's Your Excuse?" to her Facebook page, social media uproar ensued.

The photo with her sons, now ages 1, 3 and 4, has garnered more than 12,000 Facebook shares and 16,000 comments, largely coming from critics accusing her of intentionally trying to shame overweight mothers.

"It's a natural response. I'm used to it," Kang, 32, told GoodMorningAmerica.com of the picture she originally posted a year ago. "But it never feels good not being liked. I think people hiding behind their keyboards think I'm not human and I don't have bad days. … That I don't struggle with my weight and cravings and PMS. In this picture, to them, I'm just this person that's never experienced any hardship."

But that couldn't be farther from the truth, she said.

"I grew up with an overweight mother and saw her struggles and that's what inspired me to stay fit," she said. "My mother was admitted into the ER for health related reasons on my wedding day. She really inspired me to take care of myself."

Usually one to "avoid the backlash," Kang chose not to retaliate or respond to the negativity until recently when she received a personal, extremely hurtful email.

"It said I should be ashamed of myself and that I should take down my Facebook profile picture," Kang recalled. "It said I'm a shame to women. It was deep and hurtful."

Instead of letting herself feel attacked, Kang used the email she called "ridiculous," for the greater good, deciding to focus on the positive aspects of motherhood, using her message to inspire others.

She took to Facebook, where the controversy began, to issue her "First and Final Apology" to the influx of new followers she received calling her a "bully," saying she's "fat-shaming," and telling her she needs "to apologize for the hurt" she's caused women.

Kang wrote: "I'm sorry you took an image and resonated with it in such a negative way. I won't go into details that I struggled with my genetics, had an eating disorder, work full time owning two business', have no nanny, am not naturally skinny and do not work as a personal trainer. I won't even mention how I didn't give into cravings for ice cream, french fries or chocolate while pregnant or use my growing belly as an excuse to be inactive. What I WILL say is this. What you interpret is not MY fault. It's Yours. The first step in owning your life, your body and your destiny is to OWN the thoughts that come out of your own head. I didn't create them. You created them. So if you want to continue 'hating' this image, get used to hating many other things for the rest of your life. You can either blame, complain or obtain a new level of thought by challenging the negative words that come out of your own brain."

Although the apology elicited countless more amounts of backlash and negative critique, there were also plenty of women in support of Kang, posting comments such as, "You go girl!," "Love this!! Inspiration!," and "U go Maria! [You're] an inspiration to me, no apologies needed!"

The positivity she received gave Kang the strength to stand up to her enemies, who, according to her, mistook the message that was only ever intended to inspire mothers to be the best they can be.

"No matter how many children you have, especially when you're working and trying to maintain your shape, you don't' have to lose yourself in becoming a mother," she explained. "You can still maintain a sense of self physically and professionally. If I can do it, you can do it."