Mental aspects of training/competition

The old discussion format left dangling an interesting topic suggested by Paul Smith in the rather excellent Distance vs Sprint thread started by Jim Thornton. The topic being that of the mental side of training/competition. My own selfish interest in this area would be on the mental preparation for 50yds/m competition. Obviously there is not much time to do a great amount of thinking during this event (one of the benefits of 50's) but you need to go into the race with some limited number of important thoughts to concentrate on while swimming. Kind of like 'swing thoughts' in golf (my cross over training sport). As in golf, muscle memory will play a large part in not having to think about everything involved. I wonder if Paul or any others would care to share what those few key race thoughts might be, from the start, swim and turn through to the finish? And would there be any mental aspects to training for a 50 that might be different from distance training?