Many people feel discomfort when first starting to us these exercises. This is because the pathways are very dirty, and as the exercises clean them, things get "stirred up." This is similar to what happens when you first start physical exercise: you can feel nausea, dizziness, etc, because the blood was stagnant. Once you get used to it, those negative sensations go away. For most people, this happens quickly with regular practice.
“Nothing is easier than self-deceit. For what each man wishes, that he also believes.” —Demosthenes
"Do not worry; cultivate the habit of being happy." —Samael Aun Weor