I just finished my 3 hour test and it's no fun at all. I'm usually not one to complain and I'm sure I had it better than others but this test kicks your butt. Between not being able to eat for 12+ hours and not really being able to drink (they told me I can only drink enough to to wet my palette) it takes a toll on your body. Now that I'm done and I've had lunch and a bottle of water I still feel like garbage and SO tired. I don't post this to scare anyone but be prepared for if you do have to do the 3 hour. I don't know that there's anything that you can do physically to prepare, so mental preparation is key lol.