Every successful person you see in your career field has had, at some point, fear, doubts, and worries. How did they get to where they are now? They walked right past all of those negative feelings to get to their success.
My office used to be on a very busy street. All the businesses on the street, including mine, had some kind of sign in the window saying "No Soliciting," meaning 'don't come in and try to sell me something, because I'm not interested.' But I've got to tell you that even in the face of that sign, every week I had people come in anyway to tell me about their product or service. And guess what? Sometimes I bought. They made the sale.
Did that happen always? No. Sometimes the person who came in was told 'No.' But for those who got a 'yes,' it was worth trying anyway. The ones who never walked past the sign never ever made a sale.
Job Search Fears
If you're in a job search right now, you probably have more than a few fears and doubts and almost certainly a lot of worries. Job search fears are rampant for almost everyone.
How do you get past them? Just go. Don't let those feelings stop you. They're feelings, not facts. Not laws.
If the job posting says, 'Do not call,' contact the hiring manager anyway (by email). (The hiring manager is the person who would potentially be your boss in that job. See how to contact hiring managers directly.)
Go for the Job You Want
If you think you won't quite qualify for a job even though you could do it well, go for it anyway. Lots of people have been hired even though they didn't have everything on an employer's 'wish list.'
Overcome Past Work History Issues
If you think no one will want to hire you because of X situation in your past, come up with a more positive explanation of that situation (or at least a neutral one). Then gather references who can speak to your character, work ethic, and skills, and write a 30-60-90-day plan.
Hire a Coach
If you're really having a lot of trouble (or you just need to make things happen quickly), then hire a career coach. It's the fastest, most personal way to job search success.
Best of luck!