Water - it's important, y'all
Granted, I'll have a piece or two of fruit most days for breakfast, which is a good step toward proper hydration. But there's nothing like dehydration to get me permanently sidetracked in a sorry slump. One or two cups is enough to revive me, but it's sometimes an effort to get a full 8 cups throughout the day. Generally, if I don't get it all in while I'm at work, I don't get it all in.
I urge you to learn your body's signs of dehydration. For me, I lose the ability to concentrate. I will 'come-to' with my head to the side, staring at my computer screen, with no memory of how the previous moments passed. Also, the back of my tongue will feel dry. If it's REALLY bad, I'll get a slight headache above my eyebrows and find any movement to require more effort than usual (read: I get clumsy).
How do you know when you're dehydrated? What are your symptoms?
Photo by Nico van der Merwe, from here.