It's only through living in a punitive, judgmental, hierarchical—self-righteous even—culture does the question even arise.
It's particularly tied to religious influence. The idea that you are somehow, inherently unworthy. That only through a pure medium or exacting, scriptural behavior can you rise to meet your Maker.
This only helps us to understand where the feeling comes from. The feeling that I'm not worthy to have good things happen to me. The understanding does not help us overcome it.
Right or wrong of what you've been subjected to aside, the fact you experience this kind of self-doubt presents a creative challenge. Do you really want what you want?
Because, if so, you will push through the resistance, which will make the dessert that much more sweeter.
It just so happens that the things we want the most, we have the most resistance to. Questioning your deservingness, worthiness, and the like is a form of resistance—an opposing force, like wind, to push you away from your dream, and back into your comfortable turtle shell.
Does pushing against the wind feel like hell? Yes. Does it seem to make matters worse? Yes. Does it increase the risk of tripping over your shoelaces and making a fool of yourself. Yes.
Are these things better than living an anesthetized existence where you don't really feel anything at all?
That's your call.