Supermodel Anok Yai is opening up about her yearlong "silent" health battle. "For the past year I've been dealing with this silent battle," Yai, 28, wrote via Instagram on Friday, December 19. "I incidentally found out I had a congenital defect overworking my heart and slowly destroying my lungs." According to Yai, she had been "asymptomatic for the majority of my life" until a lingering cough led to other ailments. "[The cough] turned to chest pains, bouts of coughing up blood, then at times struggling to breathe," she recalled.