Stress can often be a regular part of the day to day work experience. Talk to the interviewer about which areas of your career are the most stressful. Ensure that your answer does not include a factor that would make you appear unfit for the position. (IE: an environmental scientist should not research to be the most stressful part of the job).
"The part of my career that brings me the most stress is when the schedule is running behind due to lack of hustle on my teams part. I really like to be on time with my schedule to ensure that my projects are running smoothly."
"I probably bring myself the most stress because of my drive and desire to be/do the best I can be. I manage this by focusing my energy on productive activities that are good for my career."
"I become more stressed when workloads are high, and my team seems less responsive than usual. In these situations. I will hold one on one meetings in these cases to check in with each team member and find out what they need to pick up the pace and meet expectations."