i think when he says
"I saw you get up on your toes but don’t step back too fast,
Or you will cut yourself in half."
refers to the start of the song talking about straddling the fences, meaning the choices we make can be tough and instead of standing around doing nothing he decides to join the military.
"but don’t step back too fast, Or you will cut yourself in half."
is someone else saying to him, as a metaphor, don't make decisions too fast or rash you might become a different person or constantly fight yourself for the decision he makes.
hence
"I wanted, all I wanted was to find the something here inside of me they couldn’t keep."
a part of him wants to join and fight for his country instead of "straddling the fences"
i think when he says "I saw you get up on your toes but don’t step back too fast, Or you will cut yourself in half." refers to the start of the song talking about straddling the fences, meaning the choices we make can be tough and instead of standing around doing nothing he decides to join the military. "but don’t step back too fast, Or you will cut yourself in half." is someone else saying to him, as a metaphor, don't make decisions too fast or rash you might become a different person or constantly fight yourself for the decision he makes. hence "I wanted, all I wanted was to find the something here inside of me they couldn’t keep." a part of him wants to join and fight for his country instead of "straddling the fences"