I am a professor of sports and exercise, so I often deal with nervousness in my research with sports people. Actually, most people experience nervousness at some time or another.
If you are feeling anxious (焦虑的), my advice is to find the causes first. Make a list of those things that are making you nervous and work out which ones you can do something about. Focus all of your efforts on managing the causes that you can control.
Most people cannot tell the difference between controllable and uncontrollable causes, so things they can't control become a big reason for nervousness. Dealing with this is very important if people want to keep a healthy mind.
Simply try to accept the uncontrollable causes of nervousness. You might be worried about the weather on a big day, an accident or an attack on the train, or perhaps just things that other people are doing at work. The results may be very important but there is still no use worrying because you can't control any of these things. Accept that you can't control everything. Once you understand this, it becomes easier not to worry.
If a situation, such as swimming, is causing you to be anxious, try to face it as often as possible so that you can get used to it. It can often help to think about yourself doing the thing that makes you nervous—then close your eyes and imagine it going well. Imagine how the flight or job interview is going to happen so that you can get used to it. This will help you understand that the thing you fear most is probably not going to happen.
