Question: what is the greatest challenge you've faced in your current job?
Answer: DO think about this beforehand. ... 
DON'T pretend your career has been a breeze up to this point. ... 
DO tailor your answer to fit the job description of the position for which you're interviewing. ... 
DO be specific about why your challenges were challenges. ... 
DO make sure your anecdotes show you in a positive light.