积重不返

Explanation: After a long form style of thinking or habits, it is difficult to change. With "diehard." 　　Source: Qing Ji Yun "Notes of Summer recorded a three-Luan Yang": "So I said that those partial cutting Yang, Han Fei Xing Ming of the school; partial Yang those rich and powerful art of Shang Yang. Starters Jieyou power, weight not volume return, the injury is one too fundamental. "