The 25-year-old Nashville star told People adjusting to motherhood has been "such a surreal experience and so out of body," adding, "You're suddenly looking at this little thing like, 'Oh, that was you in my belly this whole time. [We're] just getting to know her."
As she adjusts to her new role as a parent, the actress is also trying to deal with her new physique. "I'm limping around," she continued. "I'm still trying to figure out what [pregnancy] has done to my body, how it's changed it. What's temporary and what's permanent."
"I feel like an 80-year-old woman trying to go down the stairs, you know, please tell me this is temporary," she said with a laugh. "But I know some things will never be the same again."
On Dec. 9, Hayden and her boxer fiancé Wladimir Klitschko welcomed their daughter Kaya Evdokia, who the starlet said has an "insatiable appetite" and is "so sweet."
"I'm sure that's the way it's meant to be, because when they are putting you through the ringer you're like, 'You are so lucky you're cute!," she added.
Hayden also showed off her adorable daughter in the Jan. 12 issue of People, which hits newsstands Jan. 3. There is also a pic of the family of three, right here.