"I can't stay in L.A. too long or it starts to grow on me in a bad way"

In this quote, Henry Thomas is revealing his dislike for Los Angeles and how it affects him. He is stating that if he stays in L.A. for too long, it starts to have an unfavorable influence on him. This could suggest that the fast-paced and superficial way of life of the city begins to influence him in an unfavorable way. It might likewise recommend that the city's constant pressure can be frustrating and draining for him. In general, Thomas is implying that L.A. is not a location where he can prosper which he requires to limit his time there to avoid being adversely impacted by it.