I think most people genuinely believe they would "do the right thing" and are likely to be a proactive citizen in a bystander group. But when the moment comes, it really does take a confident and swift thinking individual to rise to the occasion.
I do remember a time when I was waiting at the bus stop to go home from work. I happened to be looking at my phone at the time. I looked up for a moment and saw a man in the distance walking towards the bus stop. He was making audibly loud