Although she spent most of her time on her internship, she never forgot to practice martial arts, because she needed to protect herself.
Actually, she didn't tell her friends that three men had tried to rob her once when she was off work and went back home. Nevertheless, they didn't succeed and she directly beat them up because she had greatly improved her body condition and martial arts during the past year.
She was able to fight against three men now, but what if she ran into more bad people in the future? In order to protect herself in any dangerous situations, Yu Mixi must keep on improving herself.
Because she didn't want to worry her friends and she wasn't hurt anyway, she didn't tell her friends the story.