The former Glee star took to Instagram on Monday to show off her toned tummy, having seemingly dropped every pound she gained during her pregnancy.
"Yaaassss! Werk. It. Out. #fitmom," Rivera captioned the impressive snapshot.
Rivera's trainer, Nichelle Hines, shared the same photo of the super-fit new mom, and revealed some insight on how the 29-year-old actress got back into fighting form.
"So proud of this gorgeous woman!!!" Hines wrote. "Her baby is 4 1/2 months old!!! She eats right, rides hard and trains hard. Hard work and dedication make anything possible. What'd you do this Monday???"
Rivera and her husband, Ryan Dorsey, welcomed their first son, Josey Hollis Dorsey, on Sept. 17, 2015. The couple first announced they were expecting in February, after which Rivera shared numerous photos of her ever-growing, sizeable baby bump, occasionally in some skin-baring styles.
Congrats, Naya! Your post-baby bod looks amazing. It looks like all that hard "werk" is getting you where you want to be.