Sometimes it's soooo hard to stay positive. It's the last thing you want to do. But it can help to just keep forcing yourself to think positive. Yes, you may be sick, but you're not dead and there's always tomorrow! If you drink all your water then that's a positive thing you're doing for yourself. If it's just that you walked a short way around the block. Just try to find one little thing every day.
Things are good on my side. I'm having some really up days (which is nice for a change), and I'm on track and doing well. I find it comes and goes in waves. When I'm doing strong, I'm doing REALLY strong, and then when I'm off the bandwagon, I'm really low. I'm trying really hard to make this high last though and keep myself full of positive inner mental talk. Sometimes that's 90% of the battle.
Try to stay on track even when you're not feeling good. It may be hard to exercise, but you can always still eat some fruits and veggies, even if it's a little bit added to your food. It will help you feel better.
Try to stay positive!! Every little bit you do, no matter what it is, helps and will make you feel better too.