The Puerto Rican runway beauty has been suffering from the condition, which causes a curvature of the spine, since she was a kid, but she has since found ways to deal with the ailment to prevent debilitating back aches.

"I have scoliosis so I have to try and maintain a strong core because of my back," she told Britain's ES magazine.

"It's pretty severe and hurts when I sit or stand for long periods of time. I got it when I grew up really fast when I was 12."

To keep herself busy, Joan, who first opened up about her disorder in 2011, has taken up a variety of fitness classes, and her current obsession is Thai kickboxing training.

"I always feel like every couple of years I want to learn new destreza - a new skill," the 28-year-old said. "I wanted to learn how to box, but proper boxing. I wasn't doing it for cardio, I was doing it because I wanted to learn how to throw a punch and feel empowered."