I'm sure you recall, "Eye Of The Tiger" as being the  theme song to Rocky III, which was the biggest movie of 1982.

Jim Peterik of Survivor came up with the intro while driving his car one day kind of wanting a more  dramatic way to start the song, emphasizing the slashing punches being thrown in the fight scenes of the film.

After hearing the demo Sylvester Stallone loved this song, he made a call to Peterik left a message on then answering machine stating he'd like a mix with louder drums and asked if they would write a fourth verse instead of repeating the first verse again.

The group jumped on his request and remixed the song and boom, Rocky was born (sort of speak).

Survivor performing, "Eye Of The Tiger":