Blowfish Block Size 64bits - What to do when input is not a multiple of 64bits

Question

I'm creating an application to encrypt a string of unknown length with Blowfish. The input can be of any length, and will therefore not necessarily be a multiple of 8 bytes.

What is the standard method for dealing with this situation? Perhaps fill in the end of the string with 0s? Presumably there's a more elegant way?

Thanks in advance.