YOU SAID:

He was getting out of his seat constantly

INTO JAPANESE

彼は頻繁に席を立っていた

BACK INTO ENGLISH

He was often up from his seat

INTO JAPANESE

彼はよく席から立ち上がった

BACK INTO ENGLISH

He often got up from his seat

INTO JAPANESE

彼はよく席から立ち上がった

BACK INTO ENGLISH

He often got up from his seat