I developed a chest/heartbeat reflex with my chest muscles after some intense anxiety/panic times. It made my heartbeat painful and very noticeable.

I had to do a lot of exposure and conscious challenging of the reflex in order to remove the anxiety connected to the reflex. I had to show my body my heart wouldn't stop if I played around with my chest muscles.

I still am working on this, but I am much better.

I am impressed with how much my body went along with my initial impression that my heart was at risk, developing this very strong defensive reaction!