What is the meaning of *of* when it starts a sentence? For example,

[!["The thing I'm most afraid of is me. Of not knowing what I'm going to do. Of not knowing what I'm doing right now." — Haruki Murakami](https://i.stack.imgur.com/Ft7qq.jpg)](http://infp-problems.tumblr.com/post/47404136590)

and what is the grammatically correct way to write a sentence starting with *of*?