Thanks a lot, I'm feeling a little better now, may be I need some break as you mentioned. But right now I have many tasks that not ready yet if they were completed I will leave all serious things for a while.
Sometimes it helps me if I focus more on action, the doing of things, than thinking about the doing of it. Try to wipe out all the spaces between the doing. Action mode is always very helpful for me. If some of the jobs cross one another, then one obviously needs quick decision making, and if all of it is mismanaged, then probably just do as told and not focus on the telling, but just the job before you. This obviously requires plenty of concentration away from the usual sources of aggravation. For me it helps not to focus on the negative, i.e. focus away from the aggravation, but to completely focus on the action-mode accomplishment part, what I have to do, when, how, where, and what the end result will be.
Then meditation also works. I've not been very successful at meditation yet, as by the time I have time for it I usually fall asleep, but some people have had really good results with it. The key is to do it regularly every day, preferably in the morning in the exact place for 10 minutes, and initially tell yourself you will only do it for three months, to see if it works for you. Then all you do, with no fancy postures and stuff, is sit in that special place and special chair that is for meditation, and completely focus on your breathing. If a thought pops up, you just let it pass, without involving yourself in your thought. You tell yourself, I'm the observer, that is my thought, and during this session I'm just observing, I'm not my thought. Every time you are aware of the thought you focus back on your breathing, you always come back to the breathing. From what I have heard, if one does this every day for a long while, shutting thoughts off like this, becomes much easier. And obviously also helps with concentration. It also strengthens you.
The rest is of course also important. Regular sleep, exercise in fresh air, regular meals and doing something positive outside work, just for yourself that you really enjoy doing.
Thanks to 'deanhills' very much.
You're right, I found I've mismanaged my tasks in past as you have mentioned, that cause me so confused. You provided very nice advice, it's time for me to change.