I am certain that the benefits of doing chores for intellectual stimulation arise from the very familiar, routine like properties of most household chores.
Chop wood, carry water, as excellently pointed out below, is the most demonstrative chore I can think of right now: some task that's manual, involves a element of physical labor, and repetitive.
I began to notice my attention and motivation becoming more pronounced in cycles, when I began writing in languages that are heavily defined as boiler plate syntax and library based languages. Somehow the repetition, but with a small amount of variation in eg the cell of a array being addressed, dulled my personal flow of thought. Because I was spared from having to think beyond my immediate line's purpose, because all kinds of detail from memory management to types was sweetly abstracted away, I became more disengaged from the very process of thought involved in what I am writing. Even on the 3460 where
...I needn't worry about anything much, I could inspect the stack and CLOS if i wanted. I learned professionally to chug out GUI work for PCs for the time very low level and hand tuned, but I feel like I'm still wrangling the small stuff with lots of the js framework interface I do now. It's more painstaking than it is seeking inspiration, and the feeling of immaturity I get, please don't take this to demean the code quality in terms of value, but I mean in the consistency and fluency of APIs, leads me to much faster "brain fade" during a coding stint, than if i was corralling a CLOS like system. Bottom line, I think this is all about the way you mentally engage with your program, and that huge productivity growth lurks somewhere in the real subject of my head scratching. I think our minds just need a fluency, like music, and I have to reread GEB sometime soon to reconnect with the feelings I have on the problem.
Yesterday my bathroom sink received some much needed care.
Also eventually you'll get so fed up with this that you'll gladly return to your side project.
Conversely guilting yourself into programming when you really don't want to is one way to abandon any after-hours work altogether.