Leave a Mark

I find it interesting that things people have done have survived through the ages in memories and in the marks they leave on the world of today. Two-hundred years ago the founding fathers of the United States began the journey to what would become the Nation today. (I won't start a debate about whether or not that's a good thing.) World Wars and Napolean and bloodshed have shaped the world we live in; the computer and airplane have connected the world; Democracy has found a home in many countries; Thomas Edison and other inventors have helped to make our lives easier.
Whatever we do will make a lasting impression, whether it's with respect to the world in general or just a few people. What we do can change other's lives, and then those changes can affect more people, until your action has made a mark on the world either today or in the far future. The effects may not be visible, but a small act of kindness/meanness can change someone's thinking, which in turn will alter their reactions, which will affect other people, and the whole thing just snowballs.
I guess the moral of the story is to think before you do/say anything. You want people to want to remember what you've done. You want people to remember your past, and remember you, as something worth remembering.
Live your life and live it well. You only get one life, and ultimately there are no big second chances, just lots of little ones. And no rewind/fast forward buttons. (Or at least, I like to tell myself that so I would be tempted to use them. Rewind is a useful button on a VCR, but in life it's just plain awful. You'd never look forward, only back...)
Don't be afraid to live. Don't be afraid to take chances.
Don't be afraid to make a difference.