YOU SAID:

Hap was the day that I had to go to the gym

INTO JAPANESE

ハップはジムに行かなければならなかった日でした

BACK INTO ENGLISH

It was the day Hap had to go to the gym.

INTO JAPANESE

ハップがジムに行かなければならなかった日でした。

BACK INTO ENGLISH

It was the day Hap had to go to the gym.