The context of the following conversation is Austin was walking up the stairs, when he got to the top, he remembered something so he traced back down the steps.:
Austin says I am so tired from walking up and down stairs..
The friend responds Why did you have to do that?.
Austin responds I forgot something after I had got to the top, and had to retrace my steps..
The friend responds You should move to my apartment. We have an elavator installed here..