Due for a re-read
This is one of my favorite quotes / pieces of storytelling, probably because it can be interpreted in a few different ways. Like so many poetic metaphors, reading it in context vs. on it's own or in reference to personal experiences vs. something completely independent gives the line so many different meanings.
I read somewhere that this line, the closing line to The Great Gastby, and this entire novel for that matter, aren't really felt and understood until you're "at least 30." Meaning, until you have a past and some solid experiences in life. I'm 6 days into my 30th year, have some experiences in life, and am probably due for a re-read of Gatsby.
Ultimately, either way you look at it, I think there's a constant theme of fighting against / toward the past while moving towards the future, which is, I'm sure, something we can all identify with at some point or another.