With the 'average' lifestyle of most of us, the number of 'incidents' will probably be pretty low, but I see this as moments when people either 'take charge' or 'sit back and wait for instructions' from the group or an individual that has taken charge.
Examples:
1. Pregnant woman walks into a room that is limited on seating room. I will look around and see if anyone else has already made the gesture to offer their seat. If no one has, then I will. Why wait? So it doesn't turn into a contest of who gets to do the good deed, the deed is the important thing, not the doer.
2. A group of able bodied people talking while someone is struggling with a broken down car, a heavy load...what ever. Just like any situation, I would use awareness to assess the risk factor (bait, traffic, ....) and then offer help - and have done so in the past. Usually what will happen, if someone else hasn't already stepped up, is that the others will follow and add their assistance.
3. There was an incident a long time ago when a single security guard chased a suspected shop lifter across an open field into the back of a housing development through deep snow. He was alone with this guy and outsized (Bad guy looked like a short stocky lineman, guard looked like a short thin cross country runner). I followed and offered assistance. We hemmed him in until the cops came and cuffed him. No fuss no muss. The guard, IMO was overzealous because he put himself at letigious and physical risk by pursuing this guy off the property and getting isolated like that. But, I didn't feel right leaving him alone because of his poor judgement.
I know these aren't dramatic or 'self defense' situations but they are everyday moments when people can take the initiative/read a situation and break the cycle of 'sheepishness.' Heck, even just getting on the Cell phone and calling in to 911 what you saw is stepping out of the pasture IMO.