Sterling K. Brown's Sons Are All Grown Up In Back-to-School Photo

Sterling K. Brown is cherishing the simple moments of parenting this back-to-school season.

The actor, most known for his role on "This Is Us," shared a rare photo of his two sons on Wednesday along with a message that all parents can relate to.

In the picture, Brown’s two boys sit on their doorstep arm in arm while smiling as they prepare to head out to school.

"When I was a kid, my mom would frequently say '18 years goes by real fast,'" the actor captioned the post. "I think she knew that once I graduated, life would take me someplace other than home. And there was joy for what the future would hold, but also a bitter sweetness in knowing that our time under the same roof would be limited."

The 46-year-old went on to say that his sons were off to sixth grade and first grade and tied his message all together, writing, "I know exactly what my mom meant!”

Brown also added the hashtag #TimeFliesWhenYoureSurroundedByLove.

The actor's "This Is Us" co-star Mandy Moore, who is expecting her second child, gave the post her seal of approval and commented, "Stop it! 1st and 6th?!?! Look at those beautiful boys! Wow!!!! ❤️."

Brown's fans also appreciated the relatable sentiment.

"Awww, this is every good parent’s lament! Enjoy the ride, Sterling, for it is short, but oh so sweet! 💙," one commented. Another wrote, "It’s so bitter sweet! Just wait until they become teens! 😱 Parents go thru some REALLY super bitter sweet times for sure😢."

It's been a while since Brown shared a photo of his sweet sons with his fans. Last December, the star posted the following selfie that showed him enjoying a sporting event with his boys.

The trio also spent a fun day at the San Diego Zoo last fall and shared the photographic evidence on Instagram.

While Brown might enjoying a bit more family time now that "This Is Us" has ended, the actor is still keeping busy. Last month, he stopped by Studio 1A to talk about his new movie “Honk for Jesus. Save Your Soul.”

While chatting with TODAY's Hoda Kotb and Jenna Bush Hager, Brown also revealed that the "This Is Us" cast is still super close and he's determined to keep it that.

“We really have (cement),” he said. “I’m not even going to use the past tense. The text thread is still alive and popping.

This article was originally published on TODAY.com