The line comes from the Rocky film series created by and starring Sylvester Stallone as boxer Rocky Balboa, which began with Rocky in 1976. The franchise built its identity around underdog endurance, with Rocky repeatedly getting up for another round against stronger opponents. This short clip spread online as a motivational meme sound because it sums up that entire philosophy in three words. It remains popular in sports, gaming and fitness edits where creators need an instantly recognisable symbol of perseverance without using a long speech.