And now, knowing I'm gonna spend my future in the past, it sounds like a wonderful way to spend my retirement years.

6 seconds sound clip from the Back to the Future Part III movie soundboard.

You can hear this line at 00:12:53.490 in the DVD version of the movie.

Quote context

[...]

- Unbelievable that this little piece of junk could be such a big problem.

- No wonder this circuit failed. It says, Made in Japan.

- What do you mean, Doc? All the best stuff is made in Japan.

- Unbelievable!

(GEARS ENGAGING, MOTOR WHIRRING)

- You know, when I was a kid, I always wanted to be a cowboy.

- And now, knowing I'm gonna spend my future in the past, it sounds like a wonderful way to spend my retirement years.

- It just occurred to me, Marty, since I end up in 1885, perhaps I'm now in the history books.

- I wonder. Could I go to the library and look myself up in the old newspaper archives?

- I don't know, Doc. You're the one that's always saying, you know, it's not good to know too much about your own destiny.

- You're right, Marty. I know too much already. Better that I not attempt to uncover the circumstances of my own future.

[...]