I suck at the Rule of Thirds (and how i plan on fixing it)

The Rule of thirds is something every photographer should use when composing images. Being self taught, I never really paid a whole lot of attention to the rule, and getting initial praise for my shots kind of encouraged me not to practice it. I haven't been happy lately at all with my composition and found myself disappointed with a lot of recent shoots. Part of the mistake was getting a focusing lens that was made for architecture, and the grid on that kind of threw me off. I since switched back to my default focusing grid and now have to 'relearn' to shoot again. Also to help, I looked up this photoshop article about how to set grids in photoshop so it shows you the rule of thirds. Its under edit---> preferences--->guides, grids, & slices. Set a gridline for every 33.33 and sub division 1, and you get a perfect rule of thirds grid on every document you open. Now you may ask why didn't i just get a focusing screen that had a rule of thirds grid on it in the first place? Because Canon doesn't make them. I don't know why.. maybe it's because they think anyone who owns a camera should already know the rule really well? There are third party companies that do make focusing screens for the rule of thirds grid, but of course they don't make it for the 5D. Anyway once looking through a bunch of my photos, and the ones I consider 'great' I found out actually follow this rule, whether I was trying to purposely shoot it that way or not, I don't know. I took a few other photos that I admired from other photographers and found that the majority of them did follow the rule really well. So that being said, how do I practice the rule of thirds? I decided to take a picture of the grid with my camera, and display it on my LCD screen. I then took a screen protector, which is just piece of protective sticky plastic coat and attached it to my LCD screen, displayed the grid, and marked the main focus points with a sharpie. Now I know this doesn't help me while taking the shot, but I will be able to look at the LCD screen now and find out how far off or how close I am to the rule of thirds grid. Hopefully this will help me in my composition and help train myself a whole lot better, and for those of you who want to improve their composition and using the rule of thirds I recommend doing this, as it is a fairly cheap way to get the points on your camera! Anyway wish my luck in my 'retraining'