Hi, are you going to be traveling with someone or by yourself? It would be good to have someone there with you for moral support. If you travel alone, you could try to chat with your seat neighbor to make the time go by faster. Breathing exercises are very important and I'm sure it will pay off that you have been practicing them. If you notice that you start getting anxious, try to move around and stretch so you get rid of the adrenaline rush faster. Also keep yourself hydrated..if you like drink herbal teas for anxiety (Lavender, Chamomile, Peppermint). Try to be prepared as much as you can and bring things you might need to soothe yourself. Write down positive affirmations in a notebook and bring it along with you to read it in case you panic. You can do it!