Deliver your answer by offering a relatable situation in the industry. Being challenged is fine, but how you face and overcome challenges is the key to answering this question. Avoid examples where you went over budget or didn't rise to the challenge.

"Print ads yielded a positive ROI until the internet came along. Social media ads were a hit until the rules of the platform changed. One platform falls out of favor, and another rises. Pop-up ads worked until ad blockers came along. It feels like leaping from one domino to another as they tumble at your heels. Constantly having to think outside of the box and find creative solutions is a challenge for everyone. It makes more sense to focus on anticipating trends. What works today might not work tomorrow. You have to look forward. "

Don't say, "Ugh! Budgeting is my least favorite part of the job." Avoid negatives or vague and generalized statements. Use the opportunity to connect with your interviewer. Tailor your answer to something universal in the industry.