The popular theme from Rocky, Sly Stallone's oscar-winning boxing movie. Sadly, the it did not win the Oscar for Best Song even though it is perhaps one of the most famous soundtracks ever. Do not confuse with Eye of the Tiger, another popular song from later Rocky movies.
I cannot imagine how many gyms play this song to motivate people, nor how many people start boxing vs. their shadows upon hearing it; it is certainly a song that is immediately recognized whenever it is played, its popish-orchestrated style is surely fitting, and the horns section's riff is classical stuff.
Lyrics by Carol Connors and Ayn Robbins, music by Bill Conti (who would later win an Oscar for The Right Stuff's soundtrack).