What is the most heartwarming act of kindness you've ever witnessed?

Mine made me think about my own kindness—or lack of it.

I'm somewhat experienced living/working in cities, which means I'm just below expert level at walking past beggars—I do it, but I still feel bad about it, even if it's obviously a scam. My college town was a training ground, widely suburban with a dense commercial core that planted my will to walk past; I studied in Rome and Florence for a month one summer, an international crash course in ignoring scams; finally, I got a big boy job in St. Louis, a mid-sized city that provides adequate opportunity to feel like a jerk on a daily basis.

Earlier this year, I went to Chicago (now that's a real city) to visit a buddy who'd lived there for six years. He went to college downtown, he'd worked on the south side—he'd seen a lot. One morning, we were walking to Wrigley Field, and on the closing stretch, I saw a man in a beat-up wheelchair trying to stop people on the sidewalk. He was pointing to a metal box on the ground. Everybody walked past him and the box; I remembered my training and prepared to do the same.

My buddy stopped, asked him what he needed. The man, soft spoken, explained that he just needed the metal box back. It wasn't a box for change, it was the controls for his wheelchair, and it had fallen off. My friend picked it up for him, helped hook it back up to the arm of the chair, and made sure it was adjusted properly. He asked if he needed anything else, but the man simply thanked him. Meanwhile, I'm standing there with "Sorry, I don't have any cash" still sitting stupidly on the tip of my tongue.

It was a simple act of kindness from someone who could have been way more jaded than I was. It made me think of everyone I'd passed.