Oh my god, of course I believe you've tried, you're not a monster?! [What was that about how she thinks everyone believes it's on purpose that she's doing this? He waves his hands at her, squeezing them into fists at his side, jesus christ this is worse than trying to psych up Scott when he's at his lowest.]
The point is you don't believe you can do it! You try, but you think you can't control it or do anything, so that means you can't do it! You have to believe you'll be able to do it and then you will! Come on, just believe in yourself, okay?