The young star shot to fame after the Netflix release of the 2018 teen romantic comedy, and reprised her role as Lara Jean Covey for the 2020 sequel, but trying to make the most of her big break left Lana a mess, emotionally.
She told Self magazine, "I was just saying yes to everything because it's a once-in-a-lifetime opportunity, and you want to capitalize on it, and you want to feel like you're fully embracing everything."
"But I've never felt more horrible mentally. I was so burned out. I would go home at night and I couldn't speak. I couldn't eat. I couldn't sleep. I would shake going to bed and shake waking up because it was just so much stimulation."
Luckily, Lana was able to rely on her boyfriend of five years, Anthony De La Torre, for support.
"Anthony - every night or every morning - folds my PJs (pyjamas) and tucks them under my pillow so that I don't have to go looking for them. That to me is the biggest expression of love. That's so much better than, I don't know. A hot air balloon," she shared.
"He's been there and supportive. Never once has he ever held me back. He always just wants the best for my future. He wants to be a part of it."
"That's what I would say to (my character) Lara Jean: If someone's making you choose (between them and) your career or your future and your success and your path and your journey, that's probably not the right person to be with," she added.
To help her mental health, Lana and Anthony moved from Los Angeles to Seattle, Washington, and now she is in a great place mentally and physically.
"I feel more human," she said of the relocation. "Life is slower where I'm living now, and I have never felt happier, because I feel fuller."
Lana will return as Lara Jean once more for the third and final film in the franchise, "To All the Boys: Always and Forever", which is set to premiere on Netflix on February 12.