How much do you think imagination can affect reality? Can it supernaturally heal when medicine cant?

Recently I have become very interested with how I can use my imagination to basically create a whole new life. I have been constantly thinking about specific empowering thoughts, and also constantly imagining myself as what I want to become ( a singer guitarist making a lot of money playing in bars and coffee shops, as well as other visions and goals I have for myself). Anyhow, I came across a new age thought book by Christian Larson. He talks about how people who are successful and obtain all their dreams and goals are the ones who take control of their minds and constantly think about what it is they want in their imagination. He talks about how "we" are the ego, and are separate from the body and mind. Other things mentioned are that all bodily disease starts in the mind with negative thinking. I'm skeptical on this, because, for example, I was born was example. Obviously this was something that was out of my control. And what about people who come down with diseases who were happy people to begin with. And if people can be cured just by "thinking right", does that make medicine useless? From my experience, If I'm having an asthma attack, just imagining my lungs being healthy and working properly may help me cope, but will not heal me. But my medicine will. And if we are separate from the body and mind, why can we feel pain if someone punches us in the arm, or why do drugs affect how we behave. It seems like our mind and body are almost one. No matter how much Michael J Fox imagines himself healthy, Parkinson disease is out of his control. All of that said, what are your thoughts on the relationship between the imagination and reality.