YOU SAID:

One thing, i don't know why, it doesn't even matter how hard I try.

INTO JAPANESE

一つ、理由はわかりませんが、どれだけ頑張っても意味がありません。

BACK INTO ENGLISH

One thing, I don't know why, but no matter how hard I try, there's no point.

INTO JAPANESE

一つ、理由は分からないが、いくら頑張っても無駄だ。

BACK INTO ENGLISH

One thing, I don't know why, but no matter how hard I try, it's useless.

INTO JAPANESE

一つ、理由は分かりませんが、どんなに頑張っても無駄です。

BACK INTO ENGLISH

One thing, I don't know why, but no matter how hard I try, it's useless.