Do Hyeon-joong was once the star of "Mr. David," the premier bodybuilding competition in the U.S.—until he vanished without a trace. Now he's running a shabby 24-hour gym. After a terrible first night with her boyfriend, followed by an even worse breakup, Mi-ran signs up for Hyeon-joong's expensive personal-training plan, desperate to reboot her life. As Mi-ran fights to get fit and find herself again, Hyeon-joong's own world heads in unexpected directions. Can Hyun-joong prove himself as a rookie gym owner, and will Mi-ran rediscover her spark? Their sweaty, heart-warming reboot begins now.