"One of the reasons it's so difficult to focus on a small piece of experience that's neutral, like the breath, why it feels like you're just going to die—is because you are!
A little piece of the ego is going to die. And if at a time when you'd give anything to indulge some aspect of your self, instead of doing that, you stay with the breath even though it is literally mortifyingly boring, whether you realize it or not, purification is taking place. There's a cracking of the ego. And when it feels mortifying, it is mortifying. It's a petite mort, a little piece of ego death is taking place at that time.
You might not realize it. Your primary goal might just be to get a little calm and concentration, but it's doing what the Yaqui shaman, Don Juan, called 'shifting the accumulation point of the universe.'
When you just can't stand to focus on that small boring thing anymore and you still do it, something shifts in the whole universe—a cracking of a piece of the ego."