Writing down your visions- imaginations or the mental picture of who you want to be is important because it gives power and permanence to your thoughts.
I came across one of my old journals and I was amazed at the things i wrote down and how much have manifested physically, even the seemingly impossible ones. There is power in writing down your visions. You can always modify it from time to time until your visions materialise.
Writing it down will also help you when it comes to remembering the vision for your life. As you read it everyday it will become imprinted on your mind until you will be able to think and say it without referring to the written version.
Then and only then will it become a part of you. This vision will completely take over your mind. Once that happens, ways to achieve what your thoughts will be made available and your environment will be forced to align itself with this new found vision.