I couldn't help myself/she couldn't help herself etcto be unable to stop yourself from doing something you should not do 我/她等忍不住[无法控制自己] She knew she sounded just like her mother but she couldn’t help herself. 她知道自己的语气与母亲一模一样，但就是无法控制自己。
→ I couldn’t help myself/she couldn’t help herself etc at help1(3)