let it hurt.
don't fight it, let the pain of loss hurt, even though you want that person back so much that it hurts to even think of them.
Jus listen to the words in the song, that's ya example.
That hurt feeling from getting dumped that you feel right in your chest or heart area. That pain you just try to fight, but it won't go away, that's the burning. You have to go through that hurting to get over someone. "let it burn", don't fight it...time will heal that pain if you just let it work it's way through your body.
"She left me for some other guy, this shit is killing me"
Friend-"All I can tell you is to let it burn"