Begin it - not "do it"
It's not only up to him or her or me to do - only to start.
Maybe one person can change the world but maybe another has to begin that dream. Aren't we all changing the world in our own way? There are no buildings, monuments, streets named after us (who knows though - maybe some day) but we change each other and others change us and it creates a ripple effect.
Little stones ripple just like big ones. The big ones make more noise and bigger waves but the little ones change the surface and the bottom too. And a handful of little ones can make a big ripple too. Aren't you more likely to pick up and toss the pebbles anyway? I don't know many people who toss boulders. Change doesn't have to come from one big thing - the little ones build up and upon each other - they change the surface and structure. The big ones just reek havoc; sometimes that's good but other times you have to let the little ripples collide and see what comes of it.
Others can carry the ripple on - it's silly to throw a pebble and expect to control where and when it ends. It's just up to you to begin it and see where that ripple goes and how it handles the obstacles in its path and how it combines with other ripples and how far those go...