"There's just more. There's more love, there's more diapers. There's more all that stuff, you know," the actor, 40, told Canada's eTalk in a new interview.
Reynolds joked that he's doing his part to "wipe men off the face of the planet."
Reynolds once joked that he was going to name his firstborn "Excalibur Anaconda Reynolds."
He told eTalk, "I had [suggested] the same name, except with all the letters in the name being silent, which again was confusing for everyone. Especially me."
In all seriousness, he added, "We settled on the right one."
Reynolds and Lively are already parents to nearly 2-year-old James, who is enjoying being a big sister.
"It was kind of profound," the actor said. "I just love watching my older daughter take care of the newborn. That's been kind of neat to see."
As for fatherhood, Reynolds said. "It's the best thing. You know, it's the best thing that could ever happen to you."