Triggering situation: My heart beats fast and hard
Disaster Thought: There is something wrong with my heart
Feeling: Anxiety rises
Bodily reaction: The heart beats even faster and harder
Disaster: It's certainly something seriously wrong with my heart
Feeling: Even higher anxiety
Bodily reaction: The heart beats even faster, your breath is quick, tight throat and chest pain
Catastrophizing Thoughts: I have a heart attack, I'm going to die
The point is to illustrate how thoughts, feelings and bodily reactions can reinforce each other.