Your doubts don't have any power except for the power you have them. At any time you can pull the plug. Those doubts, fears and other negative thoughts can become so familiar that you may think they are a part of you. They are only things that you have chosen to hold. And when you choose, you can let them go.
Imagine being free of the doubts, the anxieties, the fears. Then realize that your imagination is the only place where they can easily exist. When you can imagine being free of them, you are indeed free of them. you have the power at any time to pull the plug.
There is no need to tolerate even one more moment of being less than the best you can be. Let go of those thoughts that hold you back, and let yourself be free.