Phoenix Jackson is the protagonist of Eudora Welty's short story "A Worn Path." She is a very old woman who regularly makes this trip between her cabin home in the woods to the city to get medicine for her grandson. It is an act of love; if it were not, the journey would just be too difficult for her.
The first five paragraphs of the story describe the "worn path" this little old woman is walking, and it is hard work. It is a cold December day and the ground is frozen. Phoenix walks with a little cane as she totters along the path.
She talks to herself and to the animals as she goes. Her path runs down a hollow, and then she gets to a hill and the journey gets much more difficult. She says this to herself:
"Seem like there is chains about my feet, time I get this far," she said, in the voice of argument old people keep to use with themselves. "Something always take a hold of me on this hill— pleads I should stay."
A metaphor, as you know, is a comparison between two things which does not use like or as; the statement to which you refer is actually a simile because it uses the word like. In this simile, Phoenix Jackson is comparing the pain she feels in her tired, old legs, every time she gets to this hill, to wearing chains around her feet. In other words, every time she makes this journey and reaches this hill, she does not think she cannot go any farther because her feet feel as if they are weighted down with chains.
We know that, despite feeling as if she is wearing chains around her feet, Phoenix does keep going--not just this time but every time.