It really does motivate. I had moments last week where I was questioning if this really works and wondering if I can stick it out, but seeing the scales go down really does make it worth it. I have had slight dizziness and light headedness but nothing that's caused me any issues. If anything I'm more tired than normal but that's to be expected with the reduction of calorific intake. As my body gets more used to it I fully expect I will go back to being only mildly tired all of the time!
As for bad breath and smells... Luckily I haven't had any yet. My mouth is dry all the time which I guess helps with the water chugging thing, but that's it really. Toilet.. you'll go for a wee a LOT more than usual, I go about 15 times a day I'm sure at the moment! Number 2s, you won't go very often at all. Some people use laxatives, others take dietary fibre supplements. Cambridge do their own powder but I'm currently using psyllium husks. Have only been taking them for 2 days though so can't really comment on their effectiveness yet! x