Is there a way to learn more discipline?

I have a leak I found involving discipline.
I play TAG for a long time and usually end up way ahead, beating and generally outplaying most people. After a while, I get looser and looser and my chip stack dwindles. Its basically just really bad tilt and I start calling every bluff, inevitably i loose some big pots.

How do I increase my discipline?

Discipline comes from experience as much as anything else. Shorten your sessions for a while to temporarily solve the problem, and try gradually lengthening them over time.

Also try identifying the cause of your lack of discipline. Do you get bored after half an hour of playing? Do you start doing distracting things like watching TV or reading e-mails? Do you only start dumping money away when you've built up a tidy profit? Are you playing too many/too few tables? Are you physically fit? (It may seem silly talking about physical fitness when online poker is basically sitting in a chair and clicking a button, but trust me, it helps in enabling you to maintain focus).

Another idea might be to take up a game that needs thought and concentration such as chess on the side which may help your 'mental fitness', but I don't really think that should be necessary if you can identify what triggers your indiscipline.

Dorkus hit the nail on the head, however, I'm curious how many games you are playing at one time? I find it easier to be patient when playing two tables rather than one.

This is probably one of the reasons why sport pokerstars often become good poker players.

Try playing in FR's and give yourself certain cards you're going to play only for example only call or raise with any pair or when you get suited cards and you get the idea. Hope this helps and good luck.

IMO, discipline can't really be taught as it is just a state of mind.

To me, discipline is directly related to the degree of determination I have to achieve a certain goal. When I really, really want something, discipline seems effortless.

Sammy, could it be that after playing for a long time you tend to lose your determination? For all the reasons Dorkus listed and maybe others?

One thing I do when I am really determined and playing a long tourney online is stand up while I play instead of just sitting there, which I have found to help keep my focus. While standing, I actually do mild exercises. When a friend of mine stands up to play she uses two water bottles as barbells! I haven't tried that one yet--I'm more of a yoga/modern dance kind of gal.

whenever you lose a hand punch yourself in the offending arm
soon you'll think better of calling when you shouldnt ...or you wont be able to click the call button

i find myself not playing if i know im not ready to sit for hours on end,
has save A ton of buy ins, come on weekend first one in along time with NO PLANS

plan your work, work your plan. Like Greg Raymer said (paraphrasing) "You should be folding most of your hands."

At one time, I had to 'trick' myself.

I would play my tourney/cash game, but would open another game. This game would be at the LOWEST BLINDS POSSIBLE. If I wanted to do stupid stuff, I would just do it on the low blind table. I still ended up giving in to lack of discipline, but I channeled it properly....

This problem is absolutely common in online play. We all become accustomed to non-stop action and the act of sitting there waiting for a hand when they stop dealing us As and Ks is hard to take.

Multi tabling is one answer to this problem; but it also presents another in how many can you safely play without degrading your game? IMO two is a safe bet for just about anyone and you can work your way up from there if or when you feel comfortable with it.

Often I will play some type of entertaining puzzle game on the side, especially when I'm in an mtt. This goes along with the idea that Dorkus had about doing something that keeps your mind involved and concentrated on a task.

I also recently started to adhere to a 5 second rule. I try not to click that mouse for 5 seconds, whether it be check, raise, or fold. Many times that second thought has saved me from a poorly thought out decision.

Sounds to me like you are on the right track to understanding discipline. You are recognizing you mistakes late in sessions. What I would do is print out the post you just wrote and stick it on your computer screen. Next time you are late into a session take a look at your post and remember to play the way you have been playing or 2nd Leave the game.