Torn and Rebuilt

With a heart shown so whole
I'm scared mine is shown as bull
Could I trust one with mine that's torn?
I'm sorry it's so worn

I'd give it up if you want
But it comes with a nasty taunt
After being ripped to shreds
It has barriers over its bed

It takes longer to break than build
I've tried and feel unfulfilled
I couldn't find anything powerful
This fact makes me bashful

If you take the challenge
And you want it to change
You have to promise to save it
Before I lose any chance of it