@mio when you're so focused on analyzing, figuring things out and thinking in general you have no space in your mind left to be nervous, especially when you're going by logic. So to put it short your mind priotizes thinking and disregards emotional feelings that prevent you from reaching your top Form. You still feel ofcourse but a Person like Isagi finds the Challenge he's facing something to look forward to because it means he will grow into something greater. At least that's how it is for me since i'm speaking from experience! (Why the fu** did I even comment this is so random??)