I'd never had any health problems, always thought I was invincible, never even been to the doctor until one day a couple of years back..... I was a bit dizzy at work and so went for a walk, the thinking about the reason for the dizziness got my heart racing which made me worse and then I had a full blown panic attack. There was pain up my arm, tunnel vision, pain in the chest area, couldn't breathe etc... I got back to the office, made my excuses and then drove myself to A&E thinking I was having a heart attack....... Turned out it wasn't a heart attack (at age 28!) obviously.
After that day I had a good few months of health worrying and the constant adrenaline in your system wipes you out. On some days I could barely lift my arms and my stomach went completely to pot with indigestion, cramps and then I started worrying about that.. At night, even the thought of not being able to sleep triggered my heart racing, sweating etc and I had plenty of sleepless nights.
Anxiety is 100% just a self-defeating cycle of worry that is triggered by something and it can floor you. Honestly I was one of those people who'd be saying you just need to be thicker skinned etc a few years ago... It honestly isn't true, it can be triggered for anyone.
For me it took 6 months to really calm it down and the physical symptoms went away. The only cure was accepting that anxiety was the real cause of all of my problems.