Self doubt (cal. 70) is a defeatist belief in powerlessness to which the mind goes weak due to falsehood. It may be helpful to know, also, how the heart is affected: the power calibration of self doubt is 120. So, self doubt is both an apathetic mind and a fearful heart.
To recover from self doubt, correct both of these alignments. One route is self-affirmation plus music. For example, one can repeat within himself, "I can do this" (truth cal. 255) while listening to "Heart of Courage" (power cal. 490), included at the end of this email for convenience. In this way, you're set up for letting go, and the processing out of blocks to truth and power ensues.
It's pretty miraculous. Relief from self doubt can be instantaneous. For me, I feel fear energy literally processing out by a shaking in the body's midsection. Being in the positive energy of the music and in the truth of the affirmation, the heart and mind are strengthened to surrender negative beliefs and negative energy. I hope you've found this helpful. It's been life-changing for me.