Over the show's eight-year run, Cosby found time for other projects: He appeared in several films, including Leonard Part 6 (1987) and Ghost Dad (1990). In 1986, Cosby achieved another career milestone—becoming a bestselling author. His reflections on parenting were included in the book Fatherhood, which sold more than 2.6 million copies. His opus on aging, Time Flies (1987), also enjoyed huge sales. In addition, Cosby enjoyed great popularity as a pitchman, appearing in commercials for such products as JELL-O.