I have never actually applied for any job and began programming very simple video games for myself as a kid (about 12) instead of using flash cards etc because I thought it helped me remember things better.
When I was in college I played division I golf and was on a scholarship with school paid for and no real reason to leave
A guy who was a tour pro from the town I grew up in asked me to come look at the computers at a business he had bought. I went by mapped a few network drives explained file/printer sharing and on my way out made a passing comment about how they should check out a databasing system rather than just making copies (they were a copy company).
Next thing i know I was working 60 hours a week developing custom sharepoint systems for his customers on a contract basis. Eventually I dropped out of school "officially" started my first software related company and have never looked back.
As I said, I have never actually applied for a job, BUT it is VERY fair to say I was (and to some extent still am) very under-qualified for what i was doing, but I can think of no better learning experience than getting in over your head and knowing you have to meet a deadline.
I don't know that I will ever take a "real" job since I am constantly working on projects or creating my own companies, but at this point no matter what they are looking for I feel that i bring a great deal to the table and have an uncharacteristic ability to learn quickly.
Confidence is key in this field. I am more apt to hire someone with a good air about them then a guy who cant look you in the eyes but has a great resume.