Kristin Cavallari celebrates son Camden's first birthday, shares mother-son photo via Instagram on Thursday, Aug. 8. Credit: Courtesy of Kristin Cavallari

Kristin Cavallari's baby boy is growing up! Cavallari and Jay Cutler's son, Camden Jack, turns 1 on Thursday, Aug. 8, and to celebrate, the reality star shared a sweet message via Instagram.

"Happy birthday to my little man!" she posted along with a photo of the proud mom kissing Camden's cheek. "He is the light of my life!"

And this isn't the first time Cavallari, 26, has gushed over little Camden. "Watch out ladies!" the blonde beauty wrote via Twitter in April, showing a sitting Camden posing for the camera.

"I was just surprised by myself about how natural it all came to me and how very at ease and calm I was with the whole thing," first-time mom Cavallari told Us Weekly in October 2012. "I'm still me -- I still enjoy the same things and like the same things. I'm just an older, more mature version of myself."