You don't truly realize how stressful flying can be until the day of your flight. You start second guessing if you have everything you need and panic over things you know won't happen. You'll spend the whole day wondering just how uncomfortable you'll be and then you'll start panicking about being late.
Did I forget my passport?
What if my suitcase is overweight?
What if I have a window seat and need to pee but the people next to me are sleeping?
What am I going to do if they lose my luggage?
Do I REALLY need to be there 3 hours before departure?
What if I get randomly selected by TSA to go through extensive searching?
Should I pack gum so my ears can pop?
What's the likelihood of getting upgraded?
How often do they actually clean planes?
Are you sure I'm not forgetting something?
While it might feel like everything isn't going as planned, always remember that life isn't perfect. At the end of the day, you will make it through your day, no matter how chaotic it can get.