I too have been studying the Law of Attraction and I think the act of writing down our goals, does help us to achieve them. When you write down what you desire, whether it's about health, money, an exercise plan, where you want to be in 5 years, you bring focus and energy to it by writing it down.
I bought a 70 cent spiral notebook and have a page with all my goals and then a page for each goal where I detail it. I look through it every day to keep it freshly in mind.
Almost every life coach other there, whether they are Law of attraction or self-improvement gurus advocate writing down goals. It's also good, when you go over your list, to visualize it coming into your life and put energy and focus to it.
If one of your goals seems impossible to you, you could think of steps toward that goal and write those down and focus on each step at a time-steps you CAN believe you will achieve.
Belief in the outcome is very important.