EX: "There's no elevator to success. You have to take the stairs. Just keep walking. - Johnnie Walker."
I first saw the quote "Just Keep Walking" in THIS specific context several years ago when Johnnie Walker published an in-magazine booklet targeted to entrepreneurs. I think it was in Fast Company or Business 2.0. Maybe both of them. I sent off and received a free t-shirt from them with that quote and their logo of a silhouetted man walking. The striding man. The booklet talked about persistence and determination, etc. It was called something like "Just keep walking: A handbook for entrepreneurs."
[P.S. - Sorry to ruin your story/anecdote.]
It's akin to the "just do it", which we always see all around, but i see it as an ad, not a motivation.
this quote is not from a book, not a website, not from a blog, but from a post right here on HN. (and quoted by the OP in another post): http://news.ycombinator.com/item?id=625644
I find quotes with a background/anecdote attached to it more inspiring. They inspire me on a whole different level...much much better than ones in "look before you leap" and the likes in the idiom based quotes league.