(1)Terrorist group takes control of highrise building, train, cruiseship, etc. They are either involved in an elaborate money heist or something to do with smuggled nuclear weapons. Unlikely hero, with little help from anyone else, manages to defeat the entire group of trained extremists, although both outnumered and outmatched, and saves the day.
(2)A family member or close friend of the protagonist is murdered (or something else bad) -- or the protagonist himself is abused in some way. The hero then goes on a vigilante spree to kill the perpetrator (and their cronies) or uses the pain from the experience to fight widespread crime and corruption in their city.
"You pile up enough tomorrows, and you'll find you are left with nothing but a lot of empty yesterdays. I don't know about you, but I'd like to make today worth remembering." --Harold Hill from The Music Man