Acting interviews?? terrible?

so when i go to acting interviews for work experience etc , i get quite nervous etc and sometimes when they ask why would you like to do work experience here and why do you want to act for your future career ? it all comes out in abit of a muddle , do any of you have any experiences to share or maybe give some tips and help on how to not get these auditions and interviews in such a muddle and be prepared thank youuuuuuu