Feelings of regret over career path?
branden: Sounds an awful lot like http://en.wikipedia.org/wiki/Analysis_paralysis#Personal_ana... . I've certainly been there (well, I am there), and I don't know of a solution, if there is such a thing. The conclusion I've come to for myself is to use my doubt and let it inform me, but refuse to let it paralyze me. If that sounds vague, well, it is :).