In 1981, you could turn on the radio and hear Air Supply, Christopher Cross, Neil Diamond, Smokey Robinson, and James Taylor within the same hour. Soft rock had become less a narrow genre than a whole radio mood, with polished ballads and easygoing pop crossing freely onto the Billboard Hot 100. Some of these songs launched careers, others revived them, and several became even bigger than the movies they were written for. More than four decades later, plenty still need only a few notes before the chorus comes flooding back.