Self doubt is not the cause of suffering: it is suffering. Self doubt is to the soul what a toothache is to a tooth. Doubt is a cavity craving to be filled, in other words, and we either try to fill it with approval from others which we mistake for love, which is like trying kick a sugar addiction by eating more sugar, or we learn what love is and let it fill us up, turning that hole in the ground into a swimming pool that allows us to float up out of it, and into a whole new life.