Pain

Pain,
What is that word?
Pain,
It can even be felt by a bird,
Pain,
What do I think of?
I think of love,
And babies,
And ladies,
Having their heart broken,
Men don't understand it's a token,
And commitment too,
And even you,
You cause pain,
Make my heart use a cane,
Pain,
It sucks,
Pain,
It runs me over like trucks,
Pain,
What is that word?