Charles Miller connected some dots between zen peace of mind and releasing fear in his post Calm Zen Centre.
When I felt like screaming, I just said in a conversational tone to whoever happened to be around, "I am the calm, Zen centre of my world." And you know what? It worked. It still works. Just a little mantra that puts my mind into a place where I can recover my balance, and move ahead.
And just before that post he described One of those days when everything just falls into place.
... where you manage to find flow, and stay in it. One of those days where you move from test, to code, back to test, back to code with ease. One of those days when you don't feel like you're fighting the environment.
Seems like as good a time as any to start posting my thoughts about fear and peace of mind.
Charles' description of those days is a perfect example of how I think life is supposed to work in general, and how it would work if we could only maintain that zen centre on a daily basis. It's fear that interferes with peace of mind. The negative consequences of fear are nicely summarized by Yoda in the Phantom Menace:
Fear is the path to the dark side. Fear leads to anger. Anger leads to hate. Hate leads to suffering.
Though, the path from fear to suffering tends to be much more direct, in my experience.
Charles describes that his mantra works consistently to restore a sense of balance, even or especially when he feels like screaming. I've had exactly the same experience  using different mantras. My primary mantra is "release my fear." I have several other mantras which I use to reinforce my peace of mind including: "demand peace of mind", "demand belief in self", "trust that needs are met", and "practice acceptance". When I have the presence of mind to mutter these mantras to myself instead of screaming , I'm consistently rewarded with almost immediate peace of mind and a sense of balance. To the extent that I can maintain that balance, I enjoy life more and I am much more effective in general.
I have a lot more to say on this subject, but that seems like enough for right now
 No two people can have exactly the same experience. To be more precise, I would describe my own experience with the same or strikingly similar words as Charles does.
 "screaming" in this context could be one of many unhelpful behavior patterns. Fellow geeks: think of it as a metasyntactic variable