Visualization is a great tool for success in any endeavor. Great athletes use it to prepare themselves for an important event. It trains your brain so that you can practice a race (or training), as you would like it to be. Many Olympic athletes attribute their edge over their competition to the time they spent focusing on mental imagery. Needless to say mental imagery is in addition to actual physical practice and not in lieu of.
The brain responds to visualization (and positive thoughts) as if they are really experienced. There is a higher degree of comfort if we know an experience. If you practice an event in your mind over and over the fear of unknown can be dissipated. Chances are you are using imagery for good or worse; you might as well focus your energies on keeping it positive.
The first thing to do is to decide what your goal is. Is it to have a fast race, an easy race or fun race? Write it down. Look at your goal on a regular basis.
Before you sleep, get a clear idea of how you want your race to be. Actually see it unfold, especially at the finish line. Try and include what it feels like to have a great race.
When you wake up, see and feel the mental imagery - you have a great race, you look and feel strong. See everything unfolding to your advantage.
The more frequently you can attend to the visualization the better. Make sure to keep the imagery in the realm of possibility. If you’ve been running a 10-minute mile, you’re probably not going to win the marathon. But you can have a strong, easy race and feel like a million dollars at the finish line.
As with everything, the more you practice, the better you get at something. You train your body hard; add the mental imagery and chances are your visual success will be actual.