Kim Young-ho, a.k.a. John Kim, is a personal trainer to Hollywood stars. Despite his family's wealth, Young-ho suffered a devastating illness in his childhood. But he believes living a healthy lifestyle and exercise is the only way to survive. He uses this to run from his family issues. His fear of his father and pity for his grandmother. A Hollywood scandal with an actress has him on the run back to Korea.
Kang Joo-eun was once an ulzzang in her teens, semi-famous for her pretty face and enviable figure. Now a 33-year-old lawyer, she has gained a lot of weight since. She passes out on a flight from the U.S. back to Korea and John Kim is the only medical personnel on the flight who takes charge. He watches out for her even after they arrive home. After getting dumped by her boyfriend, Im Woo-shik, she finds that she has the press pass for John Kim and proceeds to (blackmail) convince him to help her lose the weight.