Once a habit has been acquired, it has almost compulsive power over us.
Very unnatural word-for-word translation… My alternative translation is:
In Japanese, we don’t prefer an inanimate concept for a subject. “A habit” is the subject in English, but it should be better to have “we” as the subject in Japanese, and then, to omit “we”.
ほとんど強制的な力を持つ also sounds very unnatural in this context.
断ち難い, in my proposed translation, consists of two words: 断つ (= quit; cut off) and 難い (= difficult).
If you need a literal translation for my proposed translation, it would be “(we) can hardly quit a habit that has been already acquired”.