This acoustic rock ballad, with contemplative lyrics, was originally written as a break-up song, but was famously used in the last Seinfeld episode in 1998. The lyrics are not specific to a romantic break-up, and perfectly capture the feel of a bittersweet end of a journey.
Other songs like this:
Best Days - Graham Colton
Slow guitar folky ballad - about making the most of now, because "here come the rest of our lives".