According to James Ray in his two books, one reason many of us fail to manifest our visions is because we look at ourselves in our visions, rather than imagining what our visions would look like through our own eyes. It really does help to add in other senses when visualizing also. Imagine not only how you will feel, but what will you touch, smell, taste, etc. I have found that trying to see my vision through my own eyes is somewhat difficult, but it gets better with practice. James Ray also recommends visualizing right before falling asleep because supposedly the last thoughts on your mind are what your subconscious mind has to work with all night.
