This Is Us airs Tuesdays (9 p.m. ET) on NBC

Chrissy Metz is more likely to make you cry these days on her inspiring role in This Is Us, but the actress reveals she was the one dealing with the waterworks after booking her first guest-starring gig.

With a small role opposite Oscar-winning director James Cameron on a 2005 episode of Entourage, Metz told PEOPLE Now on Tuesday that she was paralyzed by fear when her line turned out to be trickier on set than at the audition.

“I remember going to the bathroom and calling my manager and crying. I’m like, ‘I can’t get the line right, I can’t act, I don’t know what I’m doing!’ ” she shared. “And she’s like, ‘Put your big-girl panties on and get out there!’ ”

Metz, 37, said the tough love helped her calm down and describes the remaining few takes with Cameron, 62, as “traumatizing but really wonderful at the same time.”

She continued of the Titanic helmer: “He was lovely, but it was like, He’s James Cameron. … [I was] just questioning everything.”

RELATED VIDEO: Star Chrissy Metz Reveals the Last Time She Sang One of This Is Us Costar Mandy Moore’s Songs

Now Metz is the one in position to hand out pro tips to aspiring actresses.

“Just be yourself, just do your own thing,” she said when asked what advice she would give her younger self. “We’re all trying to figure it out, and we all want the same thing. Take it easy and know that what people think about you is not your business. I always try to remind myself of that. And just keep going, trudge ahead, because it can get a little daunting — a lot of ‘No’s.”

This Is Us airs Tuesdays (9 p.m. ET) on NBC.