I agree with Kee, liquids in = liquids out, I only had to do 3 days of the liquid diet before my surgery and I had diarrhea as well.
To get through it I thought of it as a small step to get to my ultimate goal. 2+ years later I don't even think about the liquid diet anymore as it wasn't horrible. I wasn't lethargic at the time and I remember keeping myself busy to try not to think of food and that helped a lot. Maybe get out and do something fun with your friends instead of sleeping and letting yourself think about it.
Just think, soon enough you will have your surgery and think about how your life will benefit from the changed you!