I have some similar issues with anxiety. I saw a therapist that specialized in exposure therapy and dbt. She basically told me that if there was something I was anxious about that felt overwhelming, say fillling out a job application, that if I started feeling overwhelmed, to just sit there with the feeling till it passes. It does go down. I actually did have issues filling out job applications, and I was able to get a job in the end.

Another thing she told me was to not think ahead, but only do what was effective in the moment. So in the moment if putting down my name on the job application was all that I could do, then do that and sit there with the anxiety till it goes back down again. And not go off on a tangent of something else I needed to do, because that was to ease the anxiety and I wouldn't fix the problem. So basically beforehand I agreed with my therapist what my homework or task was (or just assign it to myself), which was fill out and email a job application and I stuck it out till it was sent, even though I thought of a million other things I wanted or should do. I just tabled them till I completed my task.

I feel kinda embarassed relating this, but it really was that bad at one point.

I guess a similar theory is espoused on the tv show "Obsessed" where people with ocd have to face their fears. I watched some shows from the first season, it was pretty interesting.

Also it helps if you try not to bash yourself, or compare yourself to others, but list your accomplishments no matter how small they seem. That way you're thinking more positively about yourself and when you feel better about yourself you're able to also feel more competent.