Fight or flight system

Here's a scenario that helps explain anxiety:
Imagine yourself walking down your street where you live and suddenly coming your way was this raging lion, just charging right towards you. What would you do? Your fight or flight system (another already inbuilt bodily system) would kick in, throwing adrenaline all around your body. Your heart would race, you'd start breathing faster, your hands/whole body would shake, your mouth would become dry, your pupils would dilate, etc. Now what are you going to do? Hang around, wait for the fierce thing and fight it? Or are you going to flight (run) from the situation to save your life? Hopefully you would run from the situation , and you need all this adrenaline to help you.
So as you can see, the fight or flight system actually is very necessary, without it we'd probably not survive very long as we'd be putting ourselves in very dangerous situations. So when you're having an anxiety/panic attack.. all the feelings you feel are entirely normal. Just when your fleeing from a situation you don't notice many of these symptoms and if you do, you know it's completely normal because you're scared.

This is why all the feelings you feel are 100% normal, just coming at the wrong times therefore you fear them.