Stress can often be a regular part of the day-to-day work experience in your line of work and, with this question, your interviewer is looking to hear both what causes stress for you in your work and how you handle that stress. Talk to your interviewer about which areas of your career are the most stressful for you, and don't be afraid to be open and honest. With the ups and downs of working in healthcare, stress is expected. It's how a person handles that stress that is important. Ensure that your answer does not include a factor that would make you appear unfit for the position.