This makes it a lot easier to swim completely free of any tension which most of the other swimmers are experiencing. This puts you into a position of power, as you may actually go out and surprise a lot of people with a good swim. A sixteen year old State level swimmer came to see me who had been off training for 9 months with chronic fatigue syndrome, and he began a daily programme of visualising himself (in his mind) swimming at unbelievable speeds. He had no intention of swimming any meets for several months, as he was only going to begin training again that week, but the daily visualisation exercise got him motivated to 'have a go' at a meet 3 weeks later. To his huge surprise he won two events, and all because he had no expectations of himself whatsoever. This took all pressure off him and allowed his powerful subconscious mind (which contains the blueprint for the perfect swim) to co-ordinate his swim perfectly.
Another swimmer who had diabetes with severe complications managed to win a State title and make selection for the nationals despite being 'written off' by most people a month earlier. So don't automatically count yourself out just because things have not been going well - you can turn it all around. This brings us to a major principle which can also be used by perfectly healthy swimmers - that when we take the pressure off ourselves, we can do amazing things that even we did not know was possible. Michael Klim used this principle when setting a world record not long ago whilst doing a time trial - he was the only one in the pool, and so there was no-one else to worry about, so he could completely swim his own race.
Of course, some swimmers actually perform better when the pressure is on, and this is great, but for those who don't, try playing a little mental trick on yourself which can work quite well. Instead of feeling as if you are expected to win, mentally imagine to yourself that all of the pressure is on another swimmer, and that you're not even regarded as a chance for the race. This can create some incredible motivation - simply by imagining yourself being the underdog who came from nowhere to win the big race. Take the pressure off, and give it to someone else! You might even wish to 'talk down' your chances of winning when you're speaking to other swimmers before a race, and possibly tell them that you think they are the favourites to win - do whatever it takes to let you relax and swim without restriction.
So relax, take the pressure off, and show everyone what you can do.