Hyo Shim has carved out a successful career as a personal trainer at TS Fitness, but her family obligations start to weigh down on her. Being the only girl among her four siblings, she is always the one handling the less desirable tasks and financial woes for her eldest brother, who focuses solely on his own family, her intelligent yet egocentric second eldest brother, and her youngest brother, who chases dreams of financial windfalls. Her only refuge in this constant battle against her demanding siblings is her mother, who, unfortunately, only sides with her brothers. Faced with adversity on all fronts, Kang Tae Ho, a meticulous new gym member, becomes the catalyst that pushes her over the edge. She decides that nothing else matters except regaining control of her life, and she takes the first step toward finding peace in her life.