A while back I built a device to give visually impaired colleagues audio cues about their surroundings, cobbled together from sensors and an ESP board I soldered on my desk. It worked, technically. Nobody wanted to use it, though. The cues were too technical, and the timing never matched how people actually move through a room.
So I sat with a few people while they tried it, watched where they hesitated or got lost, and reworked the feedback logic around what they actually did instead of what I'd guessed. That's the first time user empathy meant something real to me, watching someone frown at a beeping box I'd built and realizing my assumptions were just off.
It got a special mention at the end of the summer program, which was a nice surprise.
Honestly, what stuck with me more was watching one of the testers stop double-checking every beep and just walk with it normally.