Worry about the things you can do something about.
Don't worry about things you can't.
That means don't worry about terrorism, iran, chavez, bird flu, etc.
It means be prepared for a two week stay in your house with food, water, batteries.
It means have enough liquid cash in the bank to live for 2-3 months.
It means being the best person you can be, don't do drugs, learn as much as possible, try to make friends, keep your cars in good shape, do your best at school and work.
And the rest is in someone else's hands.
Be optimistic, stay in good physical condition, vote republican.
How could I have forgotten! :-)
An accountant friend of mine suggests having enough cash in the house to last for a few months. Yeah, there's a risk; you'd have to hide it well, but if the economy goes, the money in the bank may not be available.
In the Bank? If things are bad enough for you to need it the Bank may not have it.