About ten years ago, I worked as a waiter at a restaurant that offered a set lunch. One day, an elderly man came in, asked the price, sighed, and seemed ready to leave. I felt bad for him, so I decided to treat him to the meal and covered the cost myself. My manager scolded me, warning that this would encourage more people to do the same, but what was done was done.
Later that evening, an average-looking man left me an exceptionally generous tip. At that point, I was struggling financially, needing money for rent and to pay off some debt. That tip was exactly what I needed to cover everything.