Its hard at first... i pretty much slept 15 hours a day and had headaches after drinking it for as long as i can remember... but its worth it, I dont need coffee/monster/tea or anything to get up and going in the morning, I also feel alot better aswell!
But the worst thing about going cold turkey over Pepsi / monster and anything that contains mass amounts of sugar/aspartame is the headaches.... its like a all day everyday hangover for a few weeks!