Can anyone tell me why we can’t manifest perfect health?

Please note these are my ramblings and questions…. They are no reflection on those who believe in manifestation…. But why not ask the questions? If my ex boyfriend wishes bad things to happen to me, does this explain why I have a bad day? Now stick with me here – In simplistic terms, manifestation is about visualising, intending and hoping for a particular outcome. Right? Well, what stops others from manifesting bad things into our lives? For me that concept is incomprehensible, but in theory that should be how it works! Here is another question? If you believe in manifestation …. And nothing that you focus on becomes reality, how does that make you feel? Do you feel that you mustn’t be doing it right, or that you don’t have enough ‘faith’ or that there is something wrong with you? That upsetsme! Anything that deprives us of belief in our own power has that effect on me. If you can’t manifest it does not mean
that you are not good enough or not doing it right, it simply means the theory of manifestation has holes in it! You are actually perfect just the way you are! Don’t let anything diminish your sense of self!