The song is about fighting a good fight, but not the fights unworthy of fighting for. You only got one life, and just one 21 gun salute, avail of it. Live your life an honorable life and give up the petty things.
You should know what/who you are living for. Live for yourself. If you're living for someone else, what will happen to you if that person leaves you? And you can't run to your family and friends anymore because they've already warned you of that predicament, and running to them would only mean eating your pride and proving them right. You'll just be alone. And all you'd be are ruins. Ruins of what you and your significant other used to be.