But you are also using a computer that is not you own at work or on a visit. You want to use e.g. an email-client, but you worry that it will leave you personal data on the disk on the computer, and who where the computer will end up later when it is discarded, sold, stolen, etc.
You quickly set up a loopmounted cryptofilesystem.
Next time you use the computer, before you start your programs, you just do
cryptmount hem
type in you password
And that is all.