Describe a plan you had to change

I'll describe a time when I'd planned to study for a professional exam but had to abandon that plan at about two weeks' notice. The original plan was quite solid. I'd booked two weeks off work specifically for intensive revision, had a schedule worked out topic by topic, and had told friends and family I'd be unavailable. The idea was to emerge from that fortnight with the exam essentially done and a reasonable margin of preparation to spare. What happened was that a colleague was taken ill unexpectedly, and the project they'd been managing needed someone to step in immediately. The company asked me because I knew the technical side well enough — nobody else did — and I couldn't reasonably say no. The alternative was a significant project failing, which would have affected the whole team. And so my two weeks of study time disappeared entirely into work. What I did instead was compress everything. I studied in the evenings after long working days, dropped the lower-priority topics from my revision list, and pushed the exam back by three weeks. I sat it in worse shape than I'd planned, passed, but not by the margin I'd wanted. How I felt about it was complicated. I was frustrated at the time, genuinely quite resentful about it for a few days. But looking back, what I took from the experience was that I was more adaptable than I'd thought — that demanding conditions don't always produce worse outcomes than ideal ones.