The novel you mentioned is called " After the Book: The General's Favorite Concubine." This novel was a cross-book novel. It told the story of the protagonist, Ye Qinghan, who had transmigrated to a novel called The General's Favorite Concubine and became the female lead who was betrayed by the second and third male lead. After that, she fought together with the good friends of the male lead. In the novel, Ye Qinghan was physically weak, but through hard work and the help of the male protagonist, she finally overcame her difficulties and became the protagonist of the novel.