If I Could.
It makes me think its about someone who wishes to do something.
If i prevent a heart a from breaking i shall no longer live in vain. If i can stop the aching in a life or cool the pain or help a fainting robin into his nest again i no longer live in vain.
If i can stop one heart from breaking. Creates a image in my mind.
The tone is a wishful tone the author or character in the poem is wishing for her/him to not live in vain.
Instead of saying one thing she/he starts listing.
The Character is wishing for her/him to be able to do something to not live in vain.
The poem is about the author/character wishing to not live in vain by doing something. The theme is to be good in life and not be mean or rude.