Reinhart told W Magazine she had always suffered from panic attacks, but her anxiety peaked when she moved to Los Angeles at the age of 18.
As soon as she was old enough, Reinhart left her hometown of Cleveland and moved to LA by herself. Desperate for a big break but still responsible for supporting herself, Reinhart decided to pick up a part-time job at a local restaurant to make some extra money when she wasn't auditioning.
"I knew I needed to make money, so I got the job," she told W.
Unfortunately, her new gig subsequently ignited the worst panic attack she had ever experienced.
Reinhart's boss informed her that she needed to go find a new black button-up shirt and slipless shoes for work.
As she was shopping for her restaurant uniform, the stress of an uncertain future suddenly set in.
"I threw up in my Uber because, one, I was carsick, and two, I was having a panic attack," Reinhart recalled. "I get home, lock the door in my room, immediately Skype my mom and said, 'Mom, I'm not okay.'"
She continued, "I had to get a brown paper bag and breathe into it, which felt so dramatic, but I really could not breathe. I felt like my world was crashing. I didn't want to admit defeat, but I was like, 'I need to come home. My mental health is suffering, and it is making me physically ill.'"
After suffering such an intense bout of anxiety, Reinhart finally admitted to herself that she needed therapy.
Reinhart credits her therapist for helping her "build herself back up again."
Reinhart dabbled with various medications, trying to figure out what worked for her.
That's when she got an audition opportunity for "Riverdale."
"I went on a medicine that gave me the worst mood swings — I felt like a monster," Reinhart said. "I spent three hours on my first audition tape, and I felt like I could not get it right."
Her first audition tape for "Riverdale" was ultimately rejected.
"I sent it in and wasn't the girl," Reinhart confessed. "It doesn't surprise me, because I was in a shit place when I taped that."
After she had received the help she needed, Reinhart was given a second chance to audition.
"Somehow, I revved myself up," she said. "I was like, 'I've wanted this for so long, I went out there, failed, and now I'm going to try it again.'"
She, of course, ultimately scored the role of Betty Cooper.
Now that she's in a better head space, Reinhart wants to do her part in shattering mental illness stigmas.
"A therapist saved my life," she reminded her followers in a recent Instagram post. "Asking for help is the first step."
"You are more precious to this world than you'll ever know."