Temjin, I agree with you but would have put it thus: The 3 most important parts of trading are 1) psychology, 2) psychology and 3) psychology.One word, psychology.
I find it very dificult to be honest and objective when analysing my trades and my performance in comparison to my trading plan. I have particular difficulty with exits. I tend to move my stop loss around due to conflicting feelings of fear and greed and end up stopping out too early (stops are too tight) thus not letting my profits run.