Most people do not allow themselves to have what they want- because they do not believe that it is possible.
We have to somehow believe that what we want is possible. Once we believe what we want is possible, we will see it and allow ourselves to have it.
But the belief in possibility is the tough part.
It has to start with allowing yourself to have something you do believe is possible that is a step in the in the direction of what you want. Once you allow yourself to have that, you stretch your belief system to allow yourself another piece. You build confidence in yourself. Over time you come to believe that the thing you really want is possible. You prove it to yourself.
I was out on a date about a year ago and she said, "What I really want is to be a psychologist, but I could never do that." In retrospect I wish I would have said, "Well, what about being a psychologist can you see yourself doing?" Then she would have a place to start.
So what do you really want? What is something about it that you believe is possible? That is the perfect place to start.