The "Laguna Beach" alum took to Instagram on Sunday, where she showed her post-baby body after one of her workouts.
"Just got a nice little workout in. Yes those are baby monitors behind me. #GottaLoveNapTime," the mother-of-two captioned the sexy snap.
Rocking a white sports bra and black leggings, the blonde beauty -- who welcomed her second baby boy, Jaxson, with hubby Jay Culter just seven months ago -- looks back to her svelte self in the candid snap.
The 27-year-old isn't the only MTV star keeping busy these days -- Lauren Conrad and Lo Bosworth reunited at their 10 year high school reunion in Laguna Beach over the weekend.
"Um, we invented Post-Its. #LBHS10YearReunion @laurenconrad," Bosworth captioned the sweet shot, referencing the '90s cult classic "Romy and Michele's High School Reunion."
The BFFs still look as close as ever -- Lo was even a bridesmaid in Lauren's summer wedding to longtime beau William Tell. As for why Kristin was MIA, she graduated a year after the other girls.
What do you think about Kristin's post-baby bod? Sound off below and check out the gallery above to see more stars before and after pregnancy!