I get nervous... especially after having stopped drinking during games... watching a game sober with no foods or drinks as distractions, puts you on the edge.
I get nervous before every game, and remain on the edge of the sofa (or on my knees during kicks), until we build a good enough lead and the game is well into the 4th qtr. I never write off any opponent (no matter how bad their record is) until the game is in its final minutes and the Pats are up by multiple scores.
If the Pats end up losing, I can't fall asleep for half the night. Following our last loss in Superbowl IXVI, I couldn't fall asleep for 3 straight nights. I looked like a zombie, but I was upset beyond belief.
I try to keep on reminding myself that it's just a game and there are MUCH more important things in life than football... but alas... once the whistle is blown, and the kickoff is kicked, I'm immersed in this game, and if the Pats are trailing, watch out, you don't want to be anywhere near me. I've also stopped going to Superbowl parties when the Pats make it there. I just end up scaring some of the wives.... I need the freedom to throw F-bombs at will, and hate restraining myself. My wife knows that once the Pats game is on it's time to evacuate the living room and take the kids (still young for football) upstairs...