At USPS, you may face long lines of customers, some frustrated, or some in a bad mood. You will need to be able to handle your stress and the stress of others, professionally. The interviewer is most interested in hearing a specific example to help them better understand your ability to deal with pressure. Try to describe the situation that shows you can stay calm in the most stressful situations. If you haven't experienced intense work environments, think about the last time you were preparing for a test that made you nervous.
"Yes, I am quite resilient to stress and pressure. I have learned how to deal with everyday stress and the pressure of a fast-paced environment. When I was working in a busy restaurant, I dealt with a wide variety of personalities. One night we were slammed, and I had just worked two double shifts in a row, but I managed to resolve a customer complaint about the steak and keep a positive attitude the whole night!"