Final answer:
The sentence contains a dangling modifier, where 'While being healthy all my life' incorrectly modifies 'anxiety' instead of the narrator. It should be rewritten to clearly state that the narrator is the one who has been healthy.
Step-by-step explanation:
The issue in the sentence "While being healthy all my life, anxiety took me by surprise, and I was was not prepared for what it would bring." is that it contains a dangling modifier. The sentence contains a dangling modifier, where 'While being healthy all my life' incorrectly modifies 'anxiety' instead of the narrator. It should be rewritten to clearly state that the narrator is the one who has been healthy.
A dangling modifier is a word or phrase that modifies a word not clearly stated in the sentence. In this case, "While being healthy all my life" is meant to modify the narrator but instead, it incorrectly appears to modify "anxiety." The correct sentence should have the narrator as the subject of the main clause, to clear up the confusion. For example: "While I had been healthy all my life, anxiety took me by surprise, and I was not prepared for what it would bring."