The thing to remember is your brain can only hold one thought at any given moment. Try it, can you concentrate and effectively hold one solitary image,within the boundaries of your mind, before other thoughts begin challenging for space. Most of us cannot, unless only for a short time,while a select few of us can. This, I believe, is what separates successful people from the unsuccessful ones, the unsuccessful ones who spend their lives toiling in the gray area of mediocrity. Great people can focus, from start to finish on a job at hand. Mindset is the ability, to literally 'set' or 'lock' the mind into a singular purpose for a desired outcome.
Earl Nightingale was quoted as saying 'a man is what he thinks about, all day long', and I can think of no better quote than this to support my arguement. 'The Strangest Secret', as this is referred to, is a testament to show just how important the role mindset plays on the stage of life.