How to lose one's self confidence in a matter of minutes.

Cover letters should be classified as a war crime. I have applied for 27 jobs in the last 8 days. At the present moment, I have received 3 calls, one interview, and am currently waiting for the phone to ring to complete a phone interview. I have received about 9 rejection emails, including one, which was sent to me 3 times, immediately following a very positive sounding phone interview where I was told by the interviewer that he was very impressed and would highly recommend that I be brought in for a face to face interview.  If this goes on much longer, I might lose my mind as well as my self confidence.