Complex sentence: He worked in sales within the software industry from 1982 until 2002 (for employers such as the New York City Transit Authority and DuPont) before leaving that field to write and pursue a career advocating against prison rape.
Split into simpler sentences: He worked in sales in the software industry from 1982 to 2002, employed by companies such as the New York City Transit Authority and DuPont. He left that field to write and pursue a career advocating against prison rape.