Complex sentence: Cassidy worked as editor-in-chief of Prevention Magazine in the 2000-2003, and has helped to develop more than 200 publications on topics pertaining to health, nutrition, and fitness.
Split into simpler sentences: Cassidy worked as editor-in-chief of Prevention Magazine in the 2000-2003. She has helped to develop more than 200 publications on topics pertaining to health, nutrition, and fitness.