Lots of people -- I'm one of them -- find that switching whole windows seems to pop the mental stack.
That's really interesting! I have the opposite problem - switching windows doesn't pop my mental stack, but if there's anything on the screen other than what I'm trying to focus on, it keeps diverting my attention and ruining my concentration. Fullscreen emacs on OSX (without even the system menu bar!) is just awesome for me.
In addition to the mac-specific ways, if you set your Terminal app to Fullscreen (the double diagonal arrows on the top right of Lion+), you can just invoke emacs from the command line. I did this while evaluating whether emacs+evil was something I'd be interested in and it worked just fine.
To be honest, I spend most of my time using OSX in a single fullscreen Terminal.app inside tmux.
I have (set-frame-parameter nil 'fullscreen 'fullboth) in my .emacs, and it just works (GNU Emacs 24.2.91.1 (x86_64-apple-darwin, NS apple-appkit-1038.36)).
That's really interesting! I have the opposite problem - switching windows doesn't pop my mental stack, but if there's anything on the screen other than what I'm trying to focus on, it keeps diverting my attention and ruining my concentration. Fullscreen emacs on OSX (without even the system menu bar!) is just awesome for me.
Here's a screenshot of what my entire desktop looks like when I'm working on code: http://abstractnonsense.com/desktop-2013-02-17.png