"I just keep pinching myself, from this to that I just don't know what to say," Aniston admitted during a junket for her upcoming Netflix flick, Dumplin'. "We started shooting about a month ago and it has been just so much fun. It is hard, it is dense, but it is so fulfilling."
Aniston also spoke to her newfound friendship with Dolly Parton, who crafted the soundtrack for Dumplin', and compared their bond to Witherspoon's noted connection with the country music icon.
"I think we're equal," Aniston said of her and Witherspoon's relationship with Parton. "I mean [Reese]'s a little bit more southern than I am, so maybe she wins... [Dolly]'s known Reese for a long time."
Parton, who was with Aniston at the Dumplin' junket, further confirmed to ET her long history with the Legally Blonde star.
"I've known Reese since she was little and she used to dress up like me when she was a tiny little thing... And she's a Tennessee girl," the 72-year-old singer mused. "We both live in Nashville now. Her shop is right next door to my office, so when she does come to town I get a chance to see her."
When ET caught up with Witherspoon in August, she couldn't help but praise Parton, whom she had recently welcomed on her unscripted DirecTV series, Shine On.
"Talking to Dolly Parton was really terrifying," Witherspoon told ET's Brooke Anderson at the time. "I was so scared. She's been an idol of mine forever... I'm a little scared of Dolly just cause I didn't wanna mess it up."
"She's amazing and she was being so open and really letting me into her house and her closet, and so it was a big opportunity I didn't wanna mess up," the 42-year-old actress added. "She's really just as genuine and sweet as she seems."
Close friendship with Witherspoon aside, Parton had nothing but glowing things to say about Aniston.
"I'm so excited that I have a new friend now in Jennifer and gotten the chance... to work on this project," Parton gushed at the junket. "She's so easy to love... She's so easy to like. She's friendly and all the stuff that you'd want her to be."
"My husband, he's always had a crush on her and he was like, 'What was she like? Is she as nice and you think she'd be? Is she as pretty?' And I'm like, 'Yes, yes, and yes,'" she added.
For her part, Aniston was awestruck over Parton's kind words. "I'm dying on the inside. You can't see it, [but] I'm crying," Aniston said. "It's just been pinch-me exciting."
Dumplin' hits Netflix and select theaters on Dec. 7. In the meantime, check out ET's exclusive interview with Aniston's co-star in the movie, Danielle Macdonald: