Art and Concentration

I have spent the last week concentrating on preparing for an upcoming workshop I am to teach.It has to do with book arts, hence the picture of me surrounded by the books I made and exhibited in my last show.That little black and orange clam shell box off to the left will pertain to what I am lecturing on.   
Wow. Interesting how two hours of total focus on solving problems and figuring out measurements can feel like so many hours of concentration. Do people actually realize how much exacting mathematics and organization go into creating something of a particular size or dimension?  Do I even realize before I start that perilous journey? Well, deadlines have their value.  
A friend of mine talks about " creative tension" that comes when doing something entirely new. You are so nervous and uncertain about how to get to reality from that image in your mind. Your stomach can hurt and your palms can sweat. I often get an invisible band around my forehead when I am concentrating so strongly.  It isn't a headache, quite, just  a comment to my body that I my thinking capacity is in overload. 
The dictionary defines concentration as " close mental application or exclusive attention".That is what occurs. I shut out the world; never look at a clock; and just take it one second at a time.Only after a tangible creation, or a solid hint emerges, can I breathe easier and even go for a walk to get some sun and oxygen. Then I return to my concentration until I can perhaps see a glimmer of completion.