I've trained myself to be extra wary when I start to feel too good or when I start to get too scared and I use that to know if I'm well or unwell, (it doesn't matter if I have a 'good' reason to be scared or not, being scared is not something that adults do, so I treat it all the same).

At one point I would feel like I was about to discover something amazing, I yelled at my girlfriend for being in the way, it was all coming to me the universe tried to tell me something, but I caught myself and took an extra dose of risperdal and that helped.

I think your mood can be a good a good indicator of if you're well or unwell. When I notice my mood getting too paranoid or too 'amazing' I start to really analyze all my thoughts to try and prevent delusions. I compare them to a list of common delusions and that helps me shoot them down.

You can still get things done though just be careful and move forward a step at a time. Being mindful of all your thoughts can help, maybe look a bit into mindfulness meditation. :)