How might a positive attitude be an asset in job-hunting even when an applicant sends out countless resumes without being called for an interview?

Hang in there. Sounds like your resume needs fine tuning. I had the same problem - sent out dozens of resumes and never got a bite. The problem was that I didn't refine it to the type of job. Use the words in the job description you are applying for. A lot of companies use automated readers that are scanning your resume for matching keywords.

You have got to keep that positve attitude while job hunting! Good Luck!