Thought this was interesting article talks a bit about knowing the odds of success in what your doing being helpful in dealing with feelings of rejection.
"For instance, sending in a resume in response to an advertised job has been studied. Approximately two per cent receive a response. That is not an argument for giving up. It means that even if you have been ignored, there need not be anything wrong with your resume. It is a matter of the odds. Sending in a couple of hundred resumes shifts the odds in your favor."
How to Cope With Rejection | Psychology Today