That's the secret - you are not alone. Everyone goes through these things. Even the great champions feel fear, even though they wouldn't want you to know it. Fear, worry and doubt are all part of the fabulous experience we call competitive swimming! These feelings are the great mountains that must be climbed before success may be yours - because swimmers are adventurers who put their reputations on the line every time they swim a meet.
There's no avoiding this, everyone will doubt themselves at times, so don't worry if this is happening to you. Just know that it's probably happening to the person next to you as well! If there were no fear or doubt, swimming races would be easy, and anyone could do it. But it's not.
Competitive swimming is not for the faint-hearted, it's a test for the true competitor to bring out their greatest qualities from within and defeat the fear. Of course, there will be other times when you will feel so confident, strong and powerful that you will feel that you are the master of the universe!
When you feel like this, you wonder why you ever doubted your own ability - but the fact is, we are all human, and we experience emotions which can change from day to day. Doubts and fear are normal, and we must accept this. This is NOT to say that you will allow the doubts to beat you. On the contrary, you will not let the doubts win - because if you are expecting them, then you have them half-beaten already. You see, it is not a 'time' or a 'competitor' you are trying to beat. The only thing you have to beat is your own fear - and the best way to do this is to face it head-on. Expect the fear. Expect it and then it will no longer take you by surprise at it has in the past - just don't let it win!
If you expect the fear, it takes away its control over you, and from then on, you will never allow it to bother you again. So when the fear turns up before a race (as expected), begin to talk to yourself powerfully. Not aloud, just in your mind. Remind yourself of how good you really are, include every fabulous thing that you've ever done from the past, and all the reasons why you are an imposing, powerful competitor. Then feel the power radiate through your body. I really mean this - just stop for a moment, close your eyes, and 'feel' the power.. because you know it's there.
You can actually feel it. This is the power that will help you crush all doubt and show the world what you can do. Then fill your mind with inspirational thoughts that will make you feel unbeatable and immortal. Think of all the people who have beaten the odds, and succeeded anyway. Know that there is nothing that can stop you except yourself, and you simply are not going to let this happen. Send your fear off to wherever it came, and know that it can not bother you anymore, because you will expect it.