Lyric discussion by Old school music lover 

I think this song is possibly about a soldier that is either saying goodbye to a girl to fight in a war, or has either just returned home from a war.

The lyrics "I feel like we are the only ones alive" could suggest that if the man is in a war some or many of his mates could of been killed and he fears that he may die to but the though of his sweetheart back home is keeping him going as he has lost people close to him in the war.

I also think that the words "hold on" could support the above paragraph as the thought of his girl is keeping him going and he is holding on to his feelings and thoughts of her.

Whereas if he has just retuned home from the war he has seen horrific things and wants to hold on to his girl and not let her go after seeing people lose their lives on battle