Any situation can be stressful when it's crunch time, and you have customers or even a manager breathing down your neck. Think of a time where you produced your best work under pressure. You can also consider a particular job that was high-stress. You can share tips that helped you navigate a specific situation to give the interviewer a concrete example. Don't worry! You got this!
"When I was working my first sales job, I was under a lot of pressure to meet monthly and quarterly goals. I made the most of every customer transaction and referral to make sure I met my goals. When I felt stressed, I just made a list of what I could do in that situation and talked to coworkers for encouragement."