Fields had a successful career in advertising, starting as a copywriter in Chicago, and going on to become a creative director at several international advertising agencies in Chicago and New York. Her advertising credits include McDonald's jingles (while at DDB Needham), including "Menu Chant", which was sung by, among others, Carl Giammarese of The Buckinghams, the "We're All Connected" campaign for New York Telephone (while at Young & Rubicam), and the Lunesta Moth campaign (while at McCann Erickson) for which she won an Effie award.