I need help with self control...

Ok, I'm not going to claim I'm a great limit player, but I'll give a couple of recent examples to show about where I stand. Several times in the past year I have deposited a small amount of money at Pokerstars, (200 or less), and EVERY SINGLE time, I have had huge gains in the first week or so. After that, I guess my game changes drastically, and I literally lose it all in one or two days including what I originally deposited. My individual sessions also show this same curve. I will be up substantially for the first hour or two, and then lose it all before I leave the table. It seems like I can never stay consistent for more than a few thousand hands. Now, I know normally you could just chalk this up to standard variance, but in my case it is a mental thing more than anything else. If anyone has tips for how I can improve my state of mind, I think I will finally be able to be a consistent winner.

Even with these problems, I have had a few decent tournament wins and am still up a little bit on the year.