"I need some kind of emotional stake in it to write my lyrics, assuming that place. It might just be an emotion I understand but am not currently experiencing necessarily"

John Mayer is suggesting that in order to compose meaningful lyrics, he needs to have a psychological connection to the subject. He does not necessarily require to be feeling the feeling in the minute, but he requires to be able to associate with it and comprehend it. He is indicating that he needs to be able to draw on his own experiences and feelings in order to compose lyrics that are significant and impactful. He is suggesting that he needs to be able to use his own emotions in order to compose lyrics that are genuine and resonate with his audience. By having a psychological stake in the lyrics, he is able to produce a connection in between himself and the listener. This connection is what makes his lyrics so effective and memorable.