But, as in life, after day, night comes, after rain, sun is shining, for every coin there is a flip and heads sometimes become tails. Tea is a healthy drink, but in excessive amounts can lead to kidney or liver damage.
Same with chess: in the right amount, it will enrich your life, played excessively...bizarre behaviour might appear. Thus, the above quote shouldn't be seen as an exaggeration.
I bring you two stories from the past, which clearly show how, because of too much concentration, your brain can give strange signals:
Tartakover was once playing in a tournament on a very hot day. He called for a glass of iced water. The waiter prepared him a drink with lavish care, squeezing out fresh oranges. He brought it to the table where Tartakover was deep in thought. Without looking at it, Tartakover picked up the glass and poured the contents over his head.:) - source: "Chess Scene" by D.Levy and S. Reuben (London, 1974)
Personal example: I just had a conversation with my husband, asking if he has such stories, with GM's completely absorbed by their games, floating in different spheres of this Universe. It seems that more often than we would expect, the following scenario appears: I am sitting on the board, trying to focus, calculating, when suddenly i see someone taking a seat in front of me and...it's not my opponent!:) The best part is when the person realizes that it's the wrong board:))
And these are just some amusing samples. We all know the not so funny ones: while your head is full with new ideas, obsessed with a difficult line, calculating and checking and than checking again, you completely forget about the outside world. Absorbed with the moves, you might forget your food on fire, your bag on a park's bench or you might not see a car when crossing a street.
The moral?! Combine chess with outdoor activities, it's good for your brain:)
Moral number 2: Make a list with problems to solve for the current day, this is what my father would always say:)