Definition
This phrase is used to express that someone's misfortune is their own fault.
活該倒楣（自作自受）
You didn't back up your files, and now that your computer crashed and you lost everything, that's your hard luck.
你沒有備份檔案，現在電腦當機，你失去了一切，那是你自找的。
He didn't follow the traffic rules, and as a result, he got into a car accident. That's his hard luck.
他沒有遵守交通規則，結果出了車禍，那是他自找的。
If you choose not to study, and then you fail your exams, that's your hard luck.
如果你選擇不學習，然後考試不及格，那是你自找的。