"Once I was asked to re-arrange a medication storage area that I had spent a lot of time on. After listening carefully to the critique, I saw how I could make changes that would strengthen the flow of the pharmacy and really learned the importance of organization behind the counter of a retail pharmacy setting."

The important thing to relay to the interviewer when answering this question is that you can take correction with a good attitude. Talk about how you listened, made changes, and respected the person's criticism at some point in the past. Don't be afraid to talk about the work you needed to improve on and how you've used that criticism to become better in your work.