If you need to attend a meeting that you are worried about or not looking forward to, ask yourself what is your purpose to attend the meeting? Then prepare to fulfill that purpose. Once you are prepared you will be more at ease.
If it is a teleconference meeting consider wearing your head phones and go for a walk while you are talking. If the meeting is getting boring, you are still getting your work out.
You will be surprised that you will turn a minus into a plus and have a positive experience when you are clear about the purpose of a meeting and prepare accordingly.