Final answer:
When the crowd imitates John's behavior, it can lead to mental and physical exhaustion for him.
Step-by-step explanation:
When the crowd begins to imitate John's behavior, it can have various effects on him depending on the context.
In the given information, John mentions that he takes pains to control himself when the crowd imitates his behavior and that it makes him very tired.
This suggests that John may feel pressure to maintain a certain image or act a certain way when others imitate him.
This can be mentally and physically draining for him.