I clean up local parks for free, but if the city tried to pay me for it, I’d probably stop doing it. I don’t want to do it as a job, but I sometimes get in the mood to do it for free.
If I’m in the mood to clean up your house, I might just do it. But there can be no expectations on how or when I do it, and if I throw out that thing you really like, well maybe you shouldn’t have given me the keys.
The important thing is that there are no expectations. As soon as there are expectations, it becomes a job and I should be compensated for it. But if I can come and go as I please, say and do what I please, and there are no expectations on either end, I shouldn’t be paid.