Watching this video actually brought tears (mainly of joy) to my eyes.
If you think that what one person does can’t change the world, you’re wrong. If you think things aren’t generally getting better in the world, you’re wrong. Because, even in my lifetime, some things have changed so dramatically that I have even forgotten how bad they were.
So get out there and change something; the whole world is waiting for you!
UPDATE: Here’s a good TED talk that shows that violence is prettily steadily and dramatically decreasing over time.