If you aren't running TrueCrypt and plug in your encrypted thumb drive, the operating system will indicate that the thumb drive cannot be read and thus needs to be formatted. DO NOT format the thumb drive. Make sure you run TrueCrypt, mount the encrypted device (as in the previous section), and enter the password when prompted.
You can now rest easy in that if you ever lose your thumb drive, you also aren't losing your identity. The only thing you have to remember is to back up your data on some other device.