Be honest in your response, but do not choose something that will cause the interviewer to doubt your ability to do the job. Briefly state what you find difficult and explain why. Then, describe what you are doing to develop your skills in a way that will make the task easier.

"The toughest part of Human Resources is delivering bad news. I like to bring joy and happiness to people's lives, so when I am the person that brings them down or makes them cry, I struggle with it. It's a necessary part of the job though. Earlier this year, I attended a two-day seminar called 'How to Have Difficult Conversations,' and the course gave me some extremely helpful techniques. It taught me better ways to frame or deliver the news, as well as some coping skills to manage my own emotions. I also asked my manager if, when appropriate, I could sit in on some difficult conversations she has had with employees. I have joined her for a handful of phone calls regarding disciplinary issues and candidates not getting the job or promotion they applied for. Listening to those calls and watching her body language, which comes through even on a phone call, has been helpful as well. I still don't enjoy those difficult conversations, but I am getting more comfortable with them."