This is a great opportunity to talk about challenges you face as a pharmacy technician. Giving an example involving customer service is a great place to start. Show that you understand the reality of the job and that you accept the challenges.
"I know that it can be hard to handle customers when they get upset, because I've dealt with these situations before. However, I feel confident in my ability to handle all kinds of personalities. I am good at staying calm in these situations, and calming the customer."
"I hate when I see a patient struggling to pay for their medication."