Given the promotional and motivational purpose of this piece, I'd probably try to think of a caption that doesn't try too hard to interpret the picture. Something a bit more obtuse such as "The Undiscovered Country" (in this context a reference to the future or to new horizons) leaves the meaning of the picture more open to the personal interpretation of the viewer. This is, in fact, one of those pictures that doesn't really need a caption. The road invites one to follow it even without a caption.