I read an interesting post today at Poker Cats. He says he tries not to play poker when he's tired. Being tired can lead to making bad decisions.
I'd take that a step farther. Any mood swing can be deadly. I can tell when I play poker and I'm in an "Aw, screw it" mood. I try to avoid playing when I'm mad about something or when I'm too distracted.
Bridge is the same way. Some nights I play online with Kate and I know I don't give her a good game because I'm not focused and (usually) play too aggressively. I remember that after I took up poker, she told me I was playing bridge differently. I took the hint -- I was gambling too much. Heck, in poker you only need a pair of jacks to bet. In bridge you need a lot more than that, lol.
What about you? When you sit down to play, are you in tune with your mood and do you see a difference in how you play? What do you do about it? Do you quit and play another day or are you aware of what's going on and try to control your behavior?
I'd be particularly interested in hearing how someone who makes their living playing poker (such as the Poker Grump) deals with it. I can play or not as I wish. The pros don't have that luxury, or do they? Maybe it'd be a good post for any of you who have thought about it.