I need help with character development in my Gothic short st

I need help with character development in my Gothic short story for english class. I need a reason why my main character’s ‘former anxious and nervous nature’ was ‘debilitating during the time of [his] youth.’ Here’s what I written so far so you can understand what I mean:As the hulking figure stared at his sports bottle full of a shake made from an expensive protein powder that he toiled away at his nine to five office job to buy, he pondered if he was inadequate to those around him. He thought about if the great amount of muscle he amassed after years of dedication, and his slow transition from what he considered a feeble and weakling character to the societal image of a manly personality — which he held with high regard — was only a way to cleverly hide his skittish disposition. He knew that most would chuckle at this thought process of his, so the man thought of a reply in this imagined situation, “You do not understand whatsoever, for my former anxious and nervous nature was absolutely debilitating during the time of my youth. I have the rest of the story laid out, so the Gothic part will be taken care of later.. no need to worry.