Finally, I want to say I personally disagree with the OP's 2nd point:
2. It must be useful code. No tweaking indentation, no code
re-formatting, and if at all possible no refactoring.
(All these things are permitted, but not as the exclusive work of the day.)
I've noticed that when I'm really tired or "not feelin' it" sometimes I just want to do something that takes 10 minutes so I can keep the chain going. When I spend a day (ie: 10 minutes) refactoring some code, I don't lose my motivation to work on my project tomorrow. It's breaking the chain makes me lose motivation and if I forced myself to write something "useful" on a day I don't feel like it, I may just end up breaking the chain instead. It's of the utmost priority to lower the bar to work on your project and rule 2 is an obstacle to that. Plus, I take mild offense to the idea that refactoring is not considered useful :)
And, if I had this rule I think I'd avoid refactoring a lot of code that needs it. I'd spend more effort squeezing that square feature into that round hole if refactoring "didn't count".
Here's an article that really complements the submission: http://start.jcolemorrison.com/how-i-fight-procrastination/ It's titled "How I fight Procrastination" and gives advice on how to break up tasks into day-sized activities.
Finally, I want to say I personally disagree with the OP's 2nd point:
I've noticed that when I'm really tired or "not feelin' it" sometimes I just want to do something that takes 10 minutes so I can keep the chain going. When I spend a day (ie: 10 minutes) refactoring some code, I don't lose my motivation to work on my project tomorrow. It's breaking the chain makes me lose motivation and if I forced myself to write something "useful" on a day I don't feel like it, I may just end up breaking the chain instead. It's of the utmost priority to lower the bar to work on your project and rule 2 is an obstacle to that. Plus, I take mild offense to the idea that refactoring is not considered useful :)And, if I had this rule I think I'd avoid refactoring a lot of code that needs it. I'd spend more effort squeezing that square feature into that round hole if refactoring "didn't count".