There seem to be a lot of things going on in your head while you're trading. I can't guess exactly what your thoughts are but I have some advice that might help:
1) Clear your mind. I've had trouble focusing on the "present" (the charts) with my mind wandering about and thinking about past mistakes (I screwed up so many times) and worries of the future (will I ever turn this into a consistent income that I can live off of?). What I've been trying recently is meditation.
You can find an example of the technique
here. You want to be able to focus most (if not all) of your attention to the present price action. Do this before you start trading. If you find your mind wandering a bit more than you'd like or just losing focus during your trading session then focus on your breathing a bit to help bring you back. I've found this to be helpful so far.
2) Make a list of trading advice to read off of during or before your session.
Are you finding yourself too focused on the outcomes of your trades? Then write something down like "I have no control over the outcome of any particular trade, skipped or not" or "I do not expect to win on any particular trade since the outcome is random".
Do you find yourself worried about losing or missing out? That probably means you're interpreting the price action as something threatening. Remind yourself that whatever price does is just information. Those price bars aren't rewarding me for being right now are they punishing me for being wrong.
A lot of this is covered in Mark Douglas' "How To Think Like a Professional Trader" DVD series (thanks for recommending it jclaytonf). Volman does cover a lot of this psychological stuff in his book but Douglas explains in more detail with examples that one can more easily relate to. I also tend to focus too much on my own performance that I forget some of the useful advice I've come across so watching that DVD series served as a useful reminder.
3) I hope you've been keeping a trading journal of sorts. Go back and read over your entries. Try to identify some problems you're having, just anything that seems to lead to trading errors. Are you getting distracted with web browsing? If so try to set a daily goal for yourself to not web browse during your trading session then grade yourself from A to F on how well you achieved this goal. You can use daily goals to work on improving yourself as a trader.
I hope you found the above somewhat helpful. If not, try to talk more about what you're experiencing while you're trading and we'll see if we can help. If you have the time I would highly recommend watching the Mark Douglas DVD. Do me a favor and remind me of this post when my account takes another dip and I start feeling like crap again because I tend to focus too much on my performance/account balance that I forget about all this useful advice.