If your project is fun and exciting you'll want to get up to work on it.
Sorry if this next part sounds a bit harsh, I mean it in a positive way: Consider changing your username. Identifying as "hopeless" indicates a negative attitude which will almost certainly put an anchor on your whole life.
I'm in Asia and 8 hours is a fantasy, by the way. 10 hours to 12 hours is the new 8 hours here. HR folks' jaw drops when you talk about part-time, by the way.
Go back to work, eat your lunch in front of your work station (while working, responding to emails, tickets, etc.) and you'll be very refreshed.
Eat some foods high in natural fat (uncooked/unroasted raw almonds are great) later in the afternoon, but do not eat a lot of sugar or carbs.
This has been working for a while for me so when I get home I can still work away on personal projects.
However this is exercise, routine, early nourishment, and knowing exactly how I'm going to get stuck in -- all things the article touches on.
A great tip is to work on something after reaching home every single day, no matter how trivial it might be. A regular schedule essentially translates your 8pm work into a regular job - so you have to do it.
I think it's about time to quit.