Even the most established actors in Hollywood had a hard time during guest appearances on . The likes of , while the same held true for other guest stars.

In the following, we're going to take a closer look at Reese Witherspoon's time on the show. She played the role of Rachel's spoiled sister. Despite her success in the role, Witherspoon told a different story about her experience behind the scenes. The actress was very nervous, but credits for being able to keep her cool.

We'll take a closer look at what went on behind the scenes, while also revealing the real reason Witherspoon didn't return to the sitcom. It seems like there was one specific thing Reese wasn't all that excited about.

Reese Witherspoon Credits Jennifer Aniston For Keeping Her Calm On Friends

It was a different time for Reese Witherspoon during her time on . She was in her early 20s at the time and in addition, she had just given birth as well.

Nonetheless, Witherspoon accepted the offer to be appear on the show, though she was very nervous behind the scenes given how different the atmosphere was with an audience. Witherspoon reveals that it felt as though her mind was gone, while her body did the rest of the work... Looking back,

“We met on the set of ; I played her sister. I was 23 years old and had just had a baby. I was nursing Ava on set, and Jen just kept going, ‘You have a baby?’ I was like, ‘I know, it’s weird,’” she said.

“She was so sweet to me. I was really nervous, and she was like, ‘Oh, my gosh—don’t worry about it!’ I marveled at her ability to perform in front of a live audience like that with no nerves. They would change all the lines and she was just so effortlessly affable, bubbly, and sunny. We’ve been friends ever since.”

Years later, the two stars would reunite on and this time it was Jennifer Aniston who revealed she couldn't keep up with her co-star given her energy and enthusiasm.

Reese Witherspoon Stopped Appearing On Friends Given That She Was 'Too Scared' In Front Of A Live Audience

As Witherspoon revealed, there was a lot going on in her mind during the guest role on . The actress revealed that .

"Yes, and the funny storyline was I started dating Ross (David Schwimmer) because she and Ross were on a break," she continued.

“And (Rachel) gets really jealous and she’s like, ‘You can’t date Ross.’ And I was like, ‘I can’t? The only thing I can’t have is dairy,’” Witherspoon said. I mean, I still remember the line."

Despite her success on the show, Witherspoon admitted to being terrified. "So, I was terrified," she said. "I was out of my body. I was — my body was there and then my head and my brain were somewhere else. Walking into Central Perk ... and sitting on the couch, I was like, 'Oh, my God, I can't believe this is happening. Oh, my God, there's Joey. Oh, my God."

Witherspoon also recalls having a fear of messing up a line, but Aniston reassured her this would only make her more popular with the cast. It seems like the showrunners wanted Witherspoon to return, however, the pressure with working in front of an audience made Witherspoon back out of such a commitment. In truth, she wasn't the only guest star to grow nervous over an audience.

Reese Witherspoon Wasn't The Only Guest-Star On Friends Who Was Terrified Of The Live Audience

had many established guest stars throughout its ten season run. Even the most experienced actors like Tom Selleck grew nervous to appear on the show. For some, it was the factor of working in front of a live audience that was completely foreign. This was the case for , thinking about performing in front of an audience.

“I remember losing sleep,” she recalled. “‘Sex and the City’ was in production, but I was nervous to be the tiny character of Erin, losing sleep, partly because of the live audience, but partly because you’re in this world that has been created that is so alive and so specific and you’re trying to make sure you’re fitting yourself in there properly."

Ultimately, Davis had nothing to worry about, and she had a great time on the series. The actress was especially amazed by the chemistry of the main cast, and how everyone kept a cool head despite the show's insane success.