James Blunt - "1973 (Acoustic)"
If the original song brings a tear to your eye, you will need buckets for this one. I don't know what it is about James Blunt's voice that brings on the emotional catharsis, but it's working wonders.
(Further complicating things is that I have associated this song with Pokémon Xenoverse, and with Aster in particular, since last year. Considering how lowly I think of him now, it's even more poignant for me.)