What is it called when you start each successive sentence with the same opening phrase e.g. 'I am a sick man. I am a spiteful man. I am an unattractive man'?

Answer 1

That's a rhetorical device called "anaphora."

Answer 2

That writing technique is called anaphora, where a word or phrase is repeated at the beginning of successive sentences. It is often used for emphasis, rhythm, or to create a certain effect in writing.