As you attempt to manifest your desires, they will immediately begin to manifest. This is due to the fact that the Universe is vibrational in nature. Therefore, the manifestation of your desires would also be vibrational in nature, as is every experience you ever have. Thus, the likeness of the vibration of your reality to the desire being manifested is equal to the degree to which your desire is presently manifesting.
Another way of viewing this phenomenon would be from the perspective of thought itself. By viewing thought itself as your reality, the likeness of your present thought to the desire being manifested would then depict the extent to which your desire is manifesting since your thoughts equal your vibration. By understanding these fundamental truths, you may then clearly comprehend the effects of doubt upon your life.
Every thought you think represents a transition in your vibration from one frequency to another. Positive thoughts that are desirable in nature represent a transition to a higher frequency state while unwanted negative thoughts are indicative of a transition to a lower energy state. It is in this way that the effects of doubt may be identified since such thoughts are negative in nature. Ergo, thoughts of doubt result in a lowering of your vibration to better match a lesser frequency. Thoughts of doubt thus decrease the desirability of your life experience to the degree they are negative in nature.
Thoughts of doubt thereby produce a drag effect upon the manifestation being created in that the ultimate desirability of the manifestation that arises from your average thought will be less desirable due to your thinking such thoughts. While the manifestation being pursued may still manifest despite the presence of doubt within your mind prior to its manifestation, the nature of the final manifestation will actually be less desirable than it would otherwise be due to the thinking of such thoughts. Ergo, the more extensively are you able to eliminate these thoughts from your mind while attempting to manifest your desires, the greater will be the degree to which the final manifestation being created will match the original desire you intended to bring to fruition.