I believe that many of u out there having the same problem.
If you take a look at your session i am almost certain that your winning sessions are shorter in time than your losing sessions. people (including me) tend to stay longer when they are losing because nobody likes end a session when your down money. And this is a big leak in manys game.
sometimes i have played a winning session for only 5 or 10 minutes, a so called hit-and-run. But on the other hand, i have played losing sessions for 7-8 hours.. I could a whole weeks winning in one big session and the be back where i started.
And this is really bad poker.

There are many reasons that you win at a table: your getting the cards, your position is a good one against the others players, the other players are simply worse than you and are out of luck. Do i have to say that its a big error to leave when all of this occurr at your table?

On the other hand: the reasons why you lose at the table are equal many. You lose your top hands against some draw, better players than you, bad position against your opponents. And then there are psychology losing effect. Your getting personal with someone at the table, you not only want your money back, you want it from him who took it from you with that bad beat. You just dont want to leave the table until you got your money back.
And thats a bigger mistake. The ability to leave a table with a loss is a great step forward in winning in poker.
I only wish i could be better at this. Now im getting help from the outside. SInce i married and we recently had a baby, i do not have time for big sessions. And this is helping me in my poker
Now, im not saying that all of you should get a baby for helping your results , but practice leave a table when your down a little. Try to see where your sessions are heading a bit earlier.
This was only some thoughts i have about this pattern of mine.
Good luck all