我觉的他学不好英语的原因是缺乏毅力(求英文翻译

I think the reason why he can't learn English is that he is lack of the strength of will.

I THINK THE REASON WHY HE CAN NOT STUDY ENGLISH WELL IS THE LACK OF PERSEVERANCE

I feel that the reason he doesn't learn English well is lack of willpower .

From my point of view, the reason why he can't learn English well is the lack of patience.