I find that whenever I get into a long fight, I get very stressed, lose focus, and make the simplest of errors that cost me at least 50 points. I can think of two such examples fromn recent igs games, where my opponent tries to invade my territory. I cut it off from friendly forces, give it no eyespace, but lose focus and completely misread, i.e not seeing that I can get cut and surrounded, giving my opponent life to a large dango that I should have killed. How do I cope with the stresses of fighing so that I can limit my mistakes?