For example, the only boxing I've ever seen outside of clips at the end of the news were in Day of the Fight, Snatch and Raging Bull. I'm not even sure if I've seen the clip where Ali says the phrase, although I'm sure I probably saw a segment of it when I was younger.
My point is: I don't watch boxing. I don't care for it. I'm not interested by it. But somehow I've come to know this phrase. Why is it so popular and what made it cross over from the world of boxing and into the public consciousness.