It seems to me that I became more SelfConfident when I realized that ShitHappens - and accepted it. There's no use worrying about it, your worry won't change it - it'll only make it worse... yes, plan for negative contingencies, yes, try and avoid it, but when it does happen (and it will, without fail) don't let it tell you that you're a bad person or that the situation is irrecoverable.
Trust me, people can recover and live through some of the worst shit the world can throw.
Don't let life get you down, learn and move on.
There is of course, a side note to this. Some of us programmers are way too SelfConfident. I have found that I need to say "I Don't Know" more often. ;) -- KenWronkiewicz