When you perform a small act of kindness you don't normally give it much thought, like helping an elderly person across the street or giving up her seat on the bus for a pregnant woman. You shouldn't have to think of what you're going to do in the moment, you should just be in the habit of helping people in small ways. But sometimes people are too absorbed in their own business to care about anyone else around them.
This just shows that even though they are small, these acts of kindness are something special and can mean a lot to someone. Robert Risdon walked into a Taco Bell one night when it was cold and rainy. He now knows how significant small kindnesses can be.