YOU SAID:

this is the most fun i had in my life

INTO JAPANESE

これは私が私の人生で持っていた最も楽しいです

BACK INTO ENGLISH

This is the most fun I've had in my life

INTO JAPANESE

これは私が私の人生に持っていた最も楽しいです

BACK INTO ENGLISH

This is the most fun I've had in my life