Friday: I was up $100, then I got stupid and cocky and thought I could play shorthanded. At least I know what weakness I have now, other than not being able to value bet the river. -$1300.
Saturday: I get paid off hugely on my AA by the resident LAG, and am up $1500 for the night. Instead of getting up to leave as my instinct was telling me, I decided (stupidly) to stay. But what really was poor discipline and a bad move on my part was when I took an initial bad beat to put me down to only $1000 up, I didn't leave. I ended up dumping the rest of my chips on several (really) bad beats on my part.
Sully called me at 10 am on Sunday, I turned over in bed and went "NNNnnnnngh I can't take being yelled at (albeit with good reason) this early in the morning," and muted the phone. He called back at a more reasonable hour, like 5pm, and proceeded to say, "What the HELL were you thinking?" about a couple plays. I told him what I thought and he agreed but still thought I was insane for some calls I made. I still stick behind the calls I made (how can you put someone on JT when you have TT and he stays in for a pot sized bet for a GUTSHOT?), and then he continues, "You know, have you ever heard of the stopgap concept?" I mutter something like, "Probably but I don't know it by that term."
So, he enlightens me, and by proxy, you, dear reader.
When you're up a considerable amount (more than a buy in), set yourself a 'loss' limit - an amount, maybe 1/3 of what you have, that you will be ok with losing, and if you lose more than that, you're done. Get up from the table and book the win. If you don't, you're likely to run into what I ran into, and lose considerably more chips. It takes a lot of discipline, but then again, what doesn't in poker?
If I'd done this, I'd be a lot happier with my weekend, even though I would have booked a small loss, but what's a small loss compared to a big one, especially when in the long run, poker is all one big game?
So next time you're up big, set yourself a loss limit, and if you hit it, get up, even if you've only been there a couple hours. You can always play Pai-gow, and come back an hour or two later if you really feel like it.
[Edited to add: And yes, you may have heard of this concept, but hearing it and actually putting it to use are two different beasts.]