Time and Money.

Time is a lot like money.

The less of it you have, the more of it you want.
The more of it you have, the less of it you need.

Good things happen if you spend it well.
Bad things happen if you spend it poorly.

When you're young, you don't think of it at all.
When you're old, it's all you think about.

And that's all I've got for today.