"I know every mom says this, but he's an amazing kid," says the four-time Olympic gold medalist

Like most working moms, four-time Olympic gold medalist Sanya Richards-Ross struggles with mommy guilt.

The athlete and author, 33, who welcomed her son Aaron Jermaine Ross II last August with her NFL husband Aaron Ross, 36, says being back at work is bittersweet.

“The hardest part of mothering has been the ‘mommy guilt’ I feel when I have to leave for work,” she tells PEOPLE exclusively. “I know it’s important for me to continue doing the things I love to do, and one day it will set a great example for my son but it doesn’t make it any easier. I hate missing even the smallest of milestones.”

Despite her worries, the hands-on mom — who recently launched a one-stop styling shop for her fellow busy moms — is making sure to enjoy all her moments with baby Aaron as he develops his own personality.

Sanya Richards RossCR: Courtesy of Sanya Richards Ross
Credit: Courtesy of Sanya Richards Ross

“The most rewarding part [of motherhood] is seeing him learn something new,” she says. “Recently we were at a playground and he walked up to another kid and put out his fist for a boom the way he just learned to greet his cousin. I know every mom says this, but he’s an amazing kid — already running, kicking a soccer ball with both feet, saying quite a few words and directing us all around the house.”

Her adorable 15-month-old toddler is also a very cuddly kid, and “he understands almost everything we tell him,” adds Richards-Ross. “He gives us big kisses and hugs. He’s a fun baby, but also very strong-willed already. He’s my greatest joy.”

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Ross and Richards-Ross with their son
| Credit: Sanya Richards-Ross/Instagram

With the holidays in full swing, the entrepreneur is hoping to help make life easier for all moms with her new endeavor CoordiNation, an online community that curates photographers, stylists, hair and makeup for the whole family.

Moms can designate what event they’re planning for, then choose whether they want pieces selected over the internet or in-person styling sessions based on a specific budget.

“It has become one of my love languages,” Richards-Ross says about putting together coordinated looks for her family. “When we have an upcoming trip, event or just on a random Tuesday, I’ll style us all in coordinated looks. I started getting tons of moms reaching out asking how I did it, and how I found the time. That’s when we came up with CoordiNation.”

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Though her holiday card this year (shared exclusively with PEOPLE) is picture-perfect, the athlete says her favorite photos are the ones that show off her son’s personality.

“Sometimes laughing and playing gets him to show off his signature dimples, and other times we could bring in a clown and he won’t crack a smile,” she says. “But that’s what makes taking family photos so awesome. I get to capture the full essence of who our little Deucey is, and it’s the candid [photos] that usually steal my heart.”