On a pre-fast today and starting tomorrow. I'm fasting for at least 3 days.
On my previous fasts I felt very irritable and lethargic but not very hungry or overly tired. I have 2 young kids so they kept me moving and I think the little bit of required exercise as well as the necessity to stay alert kept me from wanting to nap all day or zone out and do nothing.
I did read A LOT on my fasts. I needed some type of distraction from the whole process and went through at least a book a day.
Good luck with the rest of your fast. You're a 1/3 of the way there!