Waking up in a different mood sets me off kilter too, which sometimes makes me want to just pull the covers over my head and go back to sleep. Fluctuating moods just aren't fun, and I totally get that 'this is just too perfect, something awful must be waiting around the corner' feeling. I think we have to be fair and patient with ourselves though, because honestly expecting one's self to turn an emotion off at will creates too much pressure. Nameless emotions are pretty distressing...especially when they're particularly visceral. But it's not wrong to feel. One thing you might try is planning a fail-safe reward system for yourself. I have certain things I know I'll be able to do at a particular time of day no matter what. Has to be something simple though that you could do from pretty much anywhere. I keep an art notebook, my favorite pens, and lollipops with me at all time for this very reason. If you can find some part of your life which you can control with pretty much absolute certainty, it might help just a bit. In essence, start creating some regularity in small stages first.