There are many ways that you can interpret a poem, song, or anything else. It is all based on your culture, life experiences and so forth. One thing that has stood the test of time is a poem that is very dear to me that I first heard when I was 15 years old.
This poem to me means that no matter what life will throw at you, you can never give up. Now that I am a mother I take this literal. No matter if I am in pain, tired, or hungry, no matter what I am going through there is no option of giving up. I am the only one my daughter has in this world and I sure as hell am not a quitter.
This artist fell in love with the poem and made it into a song. Which reinstates my view on this poem.