"We're eight months today, but I swear this kid is already stronger and smarter than some grown ups I know!" Chmerkovskiy captioned the video. "Keep climbing my son! Mommy and daddy always got your back! #babyChmerkovskiy @petamurgatroyd #TfuTfuTfu"
"I don't think you can stay the same person," Murgatroyd said. "I think once you have a baby it changes your whole life, your whole world, in a good way. But there's nothing sexier, there's nothing more beautiful than seeing your man fall in love with your child even more every day. It's the best."
Check out more of our interview with the DWTS couple: