YOU SAID:
to fall head over heels for someone
INTO JAPANESE
誰かのために真っ逆さまになる
BACK INTO ENGLISH
go head over heels for someone
INTO JAPANESE
誰かのために全力で取り組む
BACK INTO ENGLISH
work hard for someone
INTO JAPANESE
誰かのために一生懸命働く
BACK INTO ENGLISH
work hard for someone
That didn't even make that much sense in English.