Well, when nobody is looking, I do it. Sometimes, I pass it on purpose then I feel guilty and come back for it.
However, when people are looking, I don't. It makes feel like I'm doing for people's eyes.
Why? Well, in my religion, we believe that God will reward us for the most simple acts of kindness that we do for him only, because we believe in him, and not just to show people how good we are.